ci: preserve Mac runner build cache with 200GB safety valve (#3249)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: QuantumExplorer

.github/workflows/tests-rs-workspace.yml

@@ -21,11 +21,21 @@ jobs:
     steps:
       - name: Check out repo
         uses: actions/checkout@v4
+        with:
+          clean: false
+
+      - name: Clean target if too large
+        run: |
+          SIZE=$(du -sm target 2>/dev/null | cut -f1 || true)
+          SIZE=${SIZE:-0}
+          echo "target/ size: ${SIZE}MB"
+          if [ "$SIZE" -gt 200000 ]; then
+            echo "target/ exceeds 200GB — cleaning"
+            cargo clean
+          fi
 
       - name: Install build dependencies
         run: |
-          # Ensure homebrew binaries take precedence over /usr/local/bin
-          # (mac-runner-2 has a broken /usr/local/bin/cmake that gets SIGKILLed)
           echo "/opt/homebrew/bin" >> $GITHUB_PATH
           echo "/opt/homebrew/opt/llvm/bin" >> $GITHUB_PATH
           brew list cmake &>/dev/null || brew install cmake