fix(ci): clippy is_multiple_of, Zephyr SDK for native_sim E2E, artifact upload resilience

- backend_reply: use is_multiple_of(2) for Clippy on stable/beta CI
- zephyr-e2e: cache + extract Zephyr SDK 0.17.4, set ZEPHYR_SDK_INSTALL_DIR
- ci: continue-on-error on binary artifact upload (transient GitHub 403)

Made-with: Cursor

Author: Alex J Lennon

.github/workflows/ci.yml

@@ -145,6 +145,7 @@ jobs:
         run: cargo build --release --verbose
 
       - name: Upload artifacts
+        continue-on-error: true
         uses: actions/upload-artifact@v4
         with:
           name: rsgdb-${{ matrix.os }}

.github/workflows/zephyr-e2e.yml

@@ -34,6 +34,9 @@ jobs:
     name: native_sim (gdbserver → rsgdb → gdb)
     runs-on: ubuntu-latest
     timeout-minutes: 90
+    env:
+      # Required by Zephyr CMake (host tools + toolchain metadata); matches Zephyr 4.x expectations.
+      ZEPHYR_SDK_INSTALL_DIR: /home/runner/zephyr-sdk-0.17.4
     steps:
       - uses: actions/checkout@v4
 
@@ -62,6 +65,23 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@stable
 
+      - name: Cache Zephyr SDK
+        id: zephyr-sdk-cache
+        uses: actions/cache@v4
+        with:
+          path: /home/runner/zephyr-sdk-0.17.4
+          key: zephyr-sdk-0.17.4-linux-x64-v1
+
+      - name: Install Zephyr SDK
+        if: steps.zephyr-sdk-cache.outputs.cache-hit != 'true'
+        run: |
+          set -euo pipefail
+          cd /tmp
+          wget -qO zephyr-sdk.tar.xz \
+            https://github.com/zephyrproject-rtos/sdk-ng/releases/download/v0.17.4/zephyr-sdk-0.17.4_linux-x86_64.tar.xz
+          tar xf zephyr-sdk.tar.xz -C /home/runner
+          # CMake finds Zephyr-sdk via ZEPHYR_SDK_INSTALL_DIR (see Zephyr SDK install docs).
+
       - name: Cache Zephyr west workspace
         uses: actions/cache@v4
         id: zephyr-cache

src/rtos/backend_reply.rs

@@ -29,7 +29,8 @@ pub fn summarize_backend_thread_payload(data: &[u8]) -> Option<String> {
     }
 
     // qThreadExtraInfo reply: hex-encoded UTF-8 name (ASCII hex digits only).
-    if data.len() >= 2 && data.len() % 2 == 0 && data.iter().all(|b| b.is_ascii_hexdigit()) {
+    if data.len() >= 2 && data.len().is_multiple_of(2) && data.iter().all(|b| b.is_ascii_hexdigit())
+    {
         if let Ok(bytes) = hex::decode(data) {
             if let Ok(text) = String::from_utf8(bytes) {
                 if text.len() <= 512 {