feat: Add Windows and Linux ARM64 CI testing

- Add rust-test-other matrix job with Windows x64 and Linux ARM64 runners
- Use runs-on service for both platforms (m7i for Windows, m7g for ARM)
- Fix Mold linker installation to be Linux-only (prevents PowerShell error on Windows)
- Enable S3 cache for Linux ARM64 runner

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>
Signed-off-by: Joe Isaacs <[email protected]>

Author: joseph-isaacs

.github/actions/setup-rust/action.yml

@@ -25,6 +25,7 @@ runs:
       run: echo "version=$(cat rust-toolchain.toml | grep channel | awk -F'\"' '{print $2}')" >> $GITHUB_OUTPUT
 
     - name: Install Mold
+      if: runner.os == 'Linux'
       uses: rui314/setup-mold@v1
 
     - name: Rust Toolchain

.github/workflows/ci.yml

@@ -400,16 +400,34 @@ jobs:
             --target x86_64-unknown-linux-gnu \
             --verbose
 
-  rust-test-windows:
-    name: "Rust tests (Windows)"
+  rust-test-other:
+    name: "Rust tests (${{ matrix.os }})"
     timeout-minutes: 120
-    runs-on:
-      - runs-on=${{ github.run_id }}
-      - family=m7i
-      - cpu=8
-      - image=windows22-full-x64
-      - tag=rust-test-windows
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: windows-x64
+            runner:
+              - runs-on=${{ github.run_id }}
+              - family=m7i
+              - cpu=8
+              - image=windows22-full-x64
+              - tag=rust-test-windows
+          - os: linux-arm64
+            runner:
+              - runs-on=${{ github.run_id }}
+              - family=m7g
+              - cpu=8
+              - image=ubuntu24-full-arm64
+              - extras=s3-cache
+              - tag=rust-test-linux-arm64
+    runs-on: ${{ matrix.runner }}
     steps:
+      - uses: runs-on/action@v2
+        if: matrix.os == 'linux-arm64'
+        with:
+          sccache: s3
       - uses: actions/checkout@v5
       - uses: ./.github/actions/setup-rust
         with: