fix: use freshly-built mcpp for test step (bootstrap lacks --mirror)

The bootstrap mcpp (from xlings cache) may not support `self config
--mirror`. Use the freshly-built binary for test + mirror config.

Author: Sunrisepeak

.github/workflows/ci.yml

@@ -88,16 +88,20 @@ jobs:
           restore-keys: |
             mcpp-target-${{ runner.os }}-
 
-      - name: Build mcpp from source (self-host)
+      - name: Configure mirror + Build mcpp from source (self-host)
         run: |
           export MCPP_VENDORED_XLINGS="$XLINGS_BIN"
+          # Set GLOBAL mirror via xlings directly (bootstrap mcpp may lack --mirror flag)
+          "$XLINGS_BIN" config --mirror GLOBAL 2>/dev/null || true
+          "$MCPP" self config --mirror GLOBAL 2>/dev/null || true
           "$MCPP" build
 
       - name: Unit + integration tests via `mcpp test`
         run: |
-          # Ensure GLOBAL mirror for package downloads (runner is outside CN)
-          "$MCPP" self config --mirror GLOBAL
-          "$MCPP" test
+          # Use freshly-built mcpp for test (it has --mirror support)
+          MCPP_FRESH=$(realpath "$(find target -type f -name mcpp -printf '%T@ %p\n' | sort -rn | head -1 | cut -d' ' -f2)")
+          "$MCPP_FRESH" self config --mirror GLOBAL
+          "$MCPP_FRESH" test
 
       - name: E2E suite
         run: |