Temporary: debug plugin install location in CI

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: JohnMcLear

.github/workflows/backend-tests.yml

@@ -58,6 +58,17 @@ jobs:
         working-directory: ./etherpad-lite
         run: |
           pnpm run plugins i --path  ../../plugin
+      - name: Debug plugin installation
+        working-directory: ./etherpad-lite
+        run: |
+          echo "=== src/plugin_packages ==="
+          find ./src/plugin_packages -type f 2>/dev/null | head -50 || echo "directory not found"
+          echo "=== node_modules/ep_* ==="
+          ls -la ./node_modules/ 2>/dev/null | grep ep_ || echo "none"
+          echo "=== src/node_modules/ep_* ==="
+          ls -la ./src/node_modules/ 2>/dev/null | grep ep_ || echo "none"
+          echo "=== find all backend specs ==="
+          find . -path "*/static/tests/backend/specs/*" 2>/dev/null || echo "none found"
       -
         name: Run the backend tests
         working-directory: ./etherpad-lite