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.

tests/commercial/pro-edition.test.ts

@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: LicenseRef-Commercial
+// Commercial-only tests — excluded from community test runs.
+
+import { describe, it, expect } from 'vitest';
+
+describe('Pro Edition', () => {
+  it('commercial test suite is reachable', () => {
+    expect(true).toBe(true);
+  });
+
+  it('AGOR_EDITION env var is set to pro when running commercial tests', () => {
+    expect(process.env.AGOR_EDITION).toBe('pro');
+  });
+});