Fix Mermaid diagrams: replace \n with <br/> for v10+ compatibility

Mermaid v10+ renders \n as literal text in node labels. Replace all
152 occurrences across 28 files with <br/> which produces proper
line breaks in the rendered diagrams.

Author: atulkhare4096

csharp-book/src/ch05-data-structures-and-collections.md

@@ -292,12 +292,12 @@ Structs in Rust are similar to classes in C#, but with some key differences arou
 ```mermaid
 graph TD
     subgraph "C# Class (Heap)"
-        CObj["Object Header\n+ vtable ptr"] --> CFields["Name: string ref\nAge: int\nHobbies: List ref"]
+        CObj["Object Header<br/>+ vtable ptr"] --> CFields["Name: string ref<br/>Age: int<br/>Hobbies: List ref"]
         CFields --> CHeap1["#quot;Alice#quot; on heap"]
         CFields --> CHeap2["List&lt;string&gt; on heap"]
     end
     subgraph "Rust Struct (Stack)"
-        RFields["name: String\n  ptr | len | cap\nage: i32\nhobbies: Vec\n  ptr | len | cap"]
+        RFields["name: String<br/>  ptr | len | cap<br/>age: i32<br/>hobbies: Vec<br/>  ptr | len | cap"]
         RFields --> RHeap1["#quot;Alice#quot; heap buffer"]
         RFields --> RHeap2["Vec heap buffer"]
     end

csharp-book/src/ch14-unsafe-rust-and-ffi.md

@@ -104,12 +104,12 @@ Rust can expose C-compatible functions that C# can call via P/Invoke.
 ```mermaid
 graph LR
     subgraph "C# Process"
-        CS["C# Code"] -->|"P/Invoke"| MI["Marshal Layer\nUTF-16 → UTF-8\nstruct layout"]
+        CS["C# Code"] -->|"P/Invoke"| MI["Marshal Layer<br/>UTF-16 → UTF-8<br/>struct layout"]
     end
     MI -->|"C ABI call"| FFI["FFI Boundary"]
     subgraph "Rust cdylib (.so / .dll)"
-        FFI --> RF["extern \"C\" fn\n#[no_mangle]"]
-        RF --> Safe["Safe Rust\ninternals"]
+        FFI --> RF["extern \"C\" fn<br/>#[no_mangle]"]
+        RF --> Safe["Safe Rust<br/>internals"]
     end
 
     style FFI fill:#fff9c4,color:#000

csharp-book/src/ch17-capstone-project.md

@@ -12,11 +12,11 @@ This capstone pulls together concepts from every part of the book. You'll build
 
 ```mermaid
 graph TD
-    CLI["main.rs\nclap CLI parser"] --> Client["client.rs\nreqwest + tokio"]
+    CLI["main.rs<br/>clap CLI parser"] --> Client["client.rs<br/>reqwest + tokio"]
     Client -->|"HTTP GET"| API["Weather API"]
-    Client -->|"JSON → struct"| Model["weather.rs\nserde Deserialize"]
-    Model --> Display["display.rs\nfmt::Display"]
-    CLI --> Err["error.rs\nthiserror"]
+    Client -->|"JSON → struct"| Model["weather.rs<br/>serde Deserialize"]
+    Model --> Display["display.rs<br/>fmt::Display"]
+    CLI --> Err["error.rs<br/>thiserror"]
     Client --> Err
 
     style CLI fill:#bbdefb,color:#000

engineering-book/src/ch01-build-scripts-buildrs-in-depth.md

@@ -544,13 +544,13 @@ flowchart TD
     START["Need compile-time work?"] -->|No| SKIP["No build.rs needed"]
     START -->|Yes| WHAT{"What kind?"}
     
-    WHAT -->|"Embed metadata"| P1["Pattern 1\nCompile-Time Constants"]
-    WHAT -->|"Compile C/C++"| P2["Pattern 2\ncc crate"]
-    WHAT -->|"Code generation"| P3["Pattern 3\nprost-build / tonic-build"]
-    WHAT -->|"Link system lib"| P4["Pattern 4\npkg-config"]
-    WHAT -->|"Detect features"| P5["Pattern 5\ncfg flags"]
+    WHAT -->|"Embed metadata"| P1["Pattern 1<br/>Compile-Time Constants"]
+    WHAT -->|"Compile C/C++"| P2["Pattern 2<br/>cc crate"]
+    WHAT -->|"Code generation"| P3["Pattern 3<br/>prost-build / tonic-build"]
+    WHAT -->|"Link system lib"| P4["Pattern 4<br/>pkg-config"]
+    WHAT -->|"Detect features"| P5["Pattern 5<br/>cfg flags"]
     
-    P1 --> RERUN["Always emit\ncargo::rerun-if-changed"]
+    P1 --> RERUN["Always emit<br/>cargo::rerun-if-changed"]
     P2 --> RERUN
     P3 --> RERUN
     P4 --> RERUN

engineering-book/src/ch02-cross-compilation-one-source-many-target.md

@@ -417,17 +417,17 @@ linker = "musl-gcc"
 flowchart TD
     START["Need to cross-compile?"] --> STATIC{"Static binary?"}
     
-    STATIC -->|Yes| MUSL["musl target\n--target x86_64-unknown-linux-musl"]
+    STATIC -->|Yes| MUSL["musl target<br/>--target x86_64-unknown-linux-musl"]
     STATIC -->|No| GLIBC{"Need old glibc?"}
     
-    GLIBC -->|Yes| ZIG["cargo-zigbuild\n--target x86_64-unknown-linux-gnu.2.17"]
+    GLIBC -->|Yes| ZIG["cargo-zigbuild<br/>--target x86_64-unknown-linux-gnu.2.17"]
     GLIBC -->|No| ARCH{"Target arch?"}
     
-    ARCH -->|"Same arch"| NATIVE["Native toolchain\nrustup target add + linker"]
+    ARCH -->|"Same arch"| NATIVE["Native toolchain<br/>rustup target add + linker"]
     ARCH -->|"ARM/other"| DOCKER{"Docker available?"}
     
-    DOCKER -->|Yes| CROSS["cross build\nDocker-based, zero setup"]
-    DOCKER -->|No| MANUAL["Manual sysroot\napt install gcc-aarch64-linux-gnu"]
+    DOCKER -->|Yes| CROSS["cross build<br/>Docker-based, zero setup"]
+    DOCKER -->|No| MANUAL["Manual sysroot<br/>apt install gcc-aarch64-linux-gnu"]
     
     style MUSL fill:#91e5a3,color:#000
     style ZIG fill:#91e5a3,color:#000

engineering-book/src/ch03-benchmarking-measuring-what-matters.md

@@ -440,13 +440,13 @@ criterion_main!(benches);
 flowchart TD
     START["Want to measure performance?"] --> WHAT{"What level?"}
 
-    WHAT -->|"Single function"| CRITERION["Criterion.rs\nStatistical, regression detection"]
-    WHAT -->|"Quick function check"| DIVAN["Divan\nLighter, attribute macros"]
-    WHAT -->|"Whole binary"| HYPERFINE["hyperfine\nEnd-to-end, wall-clock"]
-    WHAT -->|"Find hot spots"| PERF["perf + flamegraph\nCPU sampling profiler"]
+    WHAT -->|"Single function"| CRITERION["Criterion.rs<br/>Statistical, regression detection"]
+    WHAT -->|"Quick function check"| DIVAN["Divan<br/>Lighter, attribute macros"]
+    WHAT -->|"Whole binary"| HYPERFINE["hyperfine<br/>End-to-end, wall-clock"]
+    WHAT -->|"Find hot spots"| PERF["perf + flamegraph<br/>CPU sampling profiler"]
 
-    CRITERION --> CI_BENCH["Continuous benchmarking\nin GitHub Actions"]
-    PERF --> OPTIMIZE["Profile-Guided\nOptimization (PGO)"]
+    CRITERION --> CI_BENCH["Continuous benchmarking<br/>in GitHub Actions"]
+    PERF --> OPTIMIZE["Profile-Guided<br/>Optimization (PGO)"]
 
     style CRITERION fill:#91e5a3,color:#000
     style DIVAN fill:#91e5a3,color:#000

engineering-book/src/ch04-code-coverage-seeing-what-tests-miss.md

@@ -381,11 +381,11 @@ done
 flowchart TD
     START["Need code coverage?"] --> ACCURACY{"Priority?"}
     
-    ACCURACY -->|"Most accurate"| LLVM["cargo-llvm-cov\nSource-based, compiler-native"]
-    ACCURACY -->|"Quick check"| TARP["cargo-tarpaulin\nLinux only, fast"]
-    ACCURACY -->|"Multi-run aggregate"| GRCOV["grcov\nMozilla, combines profiles"]
+    ACCURACY -->|"Most accurate"| LLVM["cargo-llvm-cov<br/>Source-based, compiler-native"]
+    ACCURACY -->|"Quick check"| TARP["cargo-tarpaulin<br/>Linux only, fast"]
+    ACCURACY -->|"Multi-run aggregate"| GRCOV["grcov<br/>Mozilla, combines profiles"]
     
-    LLVM --> CI_GATE["CI coverage gate\n--fail-under-lines 80"]
+    LLVM --> CI_GATE["CI coverage gate<br/>--fail-under-lines 80"]
     TARP --> CI_GATE
     
     CI_GATE --> UPLOAD{"Upload to?"}

engineering-book/src/ch05-miri-valgrind-and-sanitizers-verifying-u.md

@@ -575,15 +575,15 @@ Least overhead                                          Most thorough
 
 ```mermaid
 flowchart TD
-    START["Have unsafe code?"] -->|No| SAFE["Safe Rust — no\nverification needed"]
+    START["Have unsafe code?"] -->|No| SAFE["Safe Rust — no<br/>verification needed"]
     START -->|Yes| KIND{"What kind?"}
     
-    KIND -->|"Pure Rust unsafe"| MIRI["Miri\nMIR interpreter\ncatches aliasing, UB, leaks"]
-    KIND -->|"FFI / C interop"| VALGRIND["Valgrind memcheck\nor ASan"]
+    KIND -->|"Pure Rust unsafe"| MIRI["Miri<br/>MIR interpreter<br/>catches aliasing, UB, leaks"]
+    KIND -->|"FFI / C interop"| VALGRIND["Valgrind memcheck<br/>or ASan"]
     KIND -->|"Concurrent unsafe"| CONC{"Lock-free?"}
     
-    CONC -->|"Atomics/lock-free"| LOOM["loom\nModel checker for atomics"]
-    CONC -->|"Mutex/shared state"| TSAN["TSan or\nMiri -Zmiri-check-number-validity"]
+    CONC -->|"Atomics/lock-free"| LOOM["loom<br/>Model checker for atomics"]
+    CONC -->|"Mutex/shared state"| TSAN["TSan or<br/>Miri -Zmiri-check-number-validity"]
     
     MIRI --> CI_MIRI["CI: cargo +nightly miri test"]
     VALGRIND --> CI_VALGRIND["CI: valgrind --leak-check=full"]

engineering-book/src/ch06-dependency-management-and-supply-chain-s.md

@@ -317,10 +317,10 @@ unknown-git = "deny"
 
 ```mermaid
 flowchart LR
-    PR["Pull Request"] --> AUDIT["cargo audit\nKnown CVEs"]
-    AUDIT --> DENY["cargo deny check\nLicenses + Bans + Sources"]
-    DENY --> OUTDATED["cargo outdated\nWeekly schedule"]
-    OUTDATED --> SEMVER["cargo semver-checks\nLibrary crates only"]
+    PR["Pull Request"] --> AUDIT["cargo audit<br/>Known CVEs"]
+    AUDIT --> DENY["cargo deny check<br/>Licenses + Bans + Sources"]
+    DENY --> OUTDATED["cargo outdated<br/>Weekly schedule"]
+    OUTDATED --> SEMVER["cargo semver-checks<br/>Library crates only"]
     
     AUDIT -->|"Fail"| BLOCK["❌ Block merge"]
     DENY -->|"Fail"| BLOCK

engineering-book/src/ch07-release-profiles-and-binary-size.md

@@ -252,13 +252,13 @@ cargo shear --fix
 ```mermaid
 flowchart TD
     START["Binary too large?"] --> STRIP{"strip = true?"}
-    STRIP -->|"No"| DO_STRIP["Add strip = true\n-50 to -70% size"]
+    STRIP -->|"No"| DO_STRIP["Add strip = true<br/>-50 to -70% size"]
     STRIP -->|"Yes"| LTO{"LTO enabled?"}
-    LTO -->|"No"| DO_LTO["Add lto = true\ncodegen-units = 1"]
-    LTO -->|"Yes"| BLOAT["Run cargo-bloat\n--crates"]
+    LTO -->|"No"| DO_LTO["Add lto = true<br/>codegen-units = 1"]
+    LTO -->|"Yes"| BLOAT["Run cargo-bloat<br/>--crates"]
     BLOAT --> BIG_DEP{"Large dependency?"}
-    BIG_DEP -->|"Yes"| REPLACE["Replace with lighter\nalternative or disable\ndefault features"]
-    BIG_DEP -->|"No"| UDEPS["cargo-udeps\nRemove unused deps"]
+    BIG_DEP -->|"Yes"| REPLACE["Replace with lighter<br/>alternative or disable<br/>default features"]
+    BIG_DEP -->|"No"| UDEPS["cargo-udeps<br/>Remove unused deps"]
     UDEPS --> OPT_LEVEL{"Need smaller?"}
     OPT_LEVEL -->|"Yes"| SIZE_OPT["opt-level = 's' or 'z'"]