Add .dockerignore and trim deny.toml unused license allowances (Task 9)

Task 9 quality-gate verification: added the .dockerignore flagged in
Task 8's review (excludes target/, .git/, .superpowers/ etc. so the
docker build context stays small — confirmed 1.5GB target/ down to
110KB transferred). cargo-deny check (run for the first time) flagged
BSD-2-Clause, ISC, and Zlib as allowed-but-unused licenses; trimmed
them per the no-blanket-allowance rule and added
unused-allowed-license = "deny" so future unjustified entries fail
loudly. All other gates (fmt, clippy -D warnings, cargo test, cargo
test --doc, cargo nextest, musl release build, docker build) passed
without needing source changes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: andysnell

.dockerignore

@@ -0,0 +1,29 @@
+# Build artifacts (large; would bloat the docker build context)
+/target
+
+# Local/IDE/AI folders
+/.idea/
+/.local/
+/.playwright-mcp/
+/.remember/
+/.superpowers/
+/.vscode/
+/.zed/
+/.git/
+/.github/
+
+# Local/IDE/OS files
+*.local.json
+*.swo
+*.swp
+*.tmp
+*~
+.DS_Store*
+._*
+Thumbs.db
+
+# Environment variable files
+.env
+*.env
+*.env.*
+!.env.dist

deny.toml

@@ -8,16 +8,18 @@
 ignore = []
 
 [licenses]
+# Only licenses actually required to satisfy a dependency's license
+# expression are listed here (verified via `cargo deny list`). BSL-1.0
+# (ryu) and Unlicense (aho-corasick, memchr) are not listed because those
+# crates' license expressions are already satisfied by MIT/Apache-2.0.
 allow = [
     "MIT",
     "Apache-2.0",
     "Apache-2.0 WITH LLVM-exception",
-    "BSD-2-Clause",
     "BSD-3-Clause",
-    "ISC",
     "Unicode-3.0",
-    "Zlib",
 ]
+unused-allowed-license = "deny"
 
 [bans]
 multiple-versions = "warn"