ci: add build workflow for every commit (syntax check + logic tests)

.github/workflows/build.yml

@@ -0,0 +1,41 @@
+name: Build
+
+on:
+  push:
+    branches:
+      - '**'          # every branch
+    tags-ignore:
+      - 'v*'          # skip tag pushes (handled by release.yml)
+  pull_request:
+
+jobs:
+  build:
+    name: Lint & Test
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
+      # Syntax-check every plugin index.js with Node's parser (no install needed)
+      - name: Syntax check all plugins
+        run: |
+          echo "=== Checking plugin syntax ==="
+          ERRORS=0
+          for f in LocalFlowPlugins/*/*/1.0.0/index.js FlowHelpers/1.0.0/*.js; do
+            node --check "$f" \
+              && echo "  ✓ $f" \
+              || { echo "  ✗ SYNTAX ERROR: $f"; ERRORS=$((ERRORS+1)); }
+          done
+          [[ $ERRORS -eq 0 ]] || { echo ""; echo "❌ $ERRORS file(s) failed syntax check."; exit 1; }
+          echo ""
+          echo "✅ All files passed syntax check."
+
+      # Run the logic test suite (no FFmpeg needed)
+      - name: Run logic tests
+        run: node tests/quick-logic-test.js