Add electron-mocha tests to regular Electron workflow

Matches the electron-arm64 workflow - uses electron-mocha to run
the full test suite with Electron's Node runtime.

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

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Author: rathboma

.github/workflows/electron.yml

@@ -57,11 +57,14 @@ jobs:
       run: npm install
 
     - name: Install Electron rebuild tools
-      run: npm install --save-dev @electron/rebuild electron@${{ matrix.electron-version }}
+      run: npm install --save-dev @electron/rebuild electron@${{ matrix.electron-version }} electron-mocha
 
     - name: Rebuild for Electron
       run: npx @electron/rebuild --version ${{ matrix.electron-version }}
 
+    - name: Run tests with Electron
+      run: npx electron-mocha --no-sandbox test/**/*.test.js --timeout 10000
+
     - name: Show build output
       shell: bash
       run: |