feat: add agor-pro commercial plugin crate and dual-repo infrastructure

agor-pro Tauri 2.x plugin (feature-gated via --features pro),
commercial Tauri config overlay, asymmetric test setup,
CI workflows (leak-check, commercial-build, PAT health),
pre-push hook, Makefile, CONTRIBUTING/MAINTENANCE/LICENSE-COMMERCIAL.

.github/workflows/commercial-build.yml

@@ -0,0 +1,71 @@
+name: Commercial Build
+
+on:
+  push:
+    branches:
+      - 'commercial/**'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  commercial-build:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            libwebkit2gtk-4.1-dev \
+            libgtk-3-dev \
+            libayatana-appindicator3-dev \
+            librsvg2-dev \
+            libssl-dev \
+            build-essential \
+            pkg-config
+
+      - name: Setup Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache Cargo
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-pro-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-pro-
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+
+      - name: Install npm dependencies
+        run: npm ci
+
+      - name: Cargo check (pro features)
+        run: cargo check --features pro
+
+      - name: Cargo test (pro features)
+        run: cargo test --features pro
+
+      - name: Vitest (frontend)
+        run: npm run test
+
+      - name: Commercial tests
+        run: |
+          if [ -d "tests/commercial/" ] && ls tests/commercial/*.test.* 2>/dev/null; then
+            npx vitest run tests/commercial/
+          else
+            echo "No commercial tests found, skipping."
+          fi