feat(extension): add Firefox WebExtension support

- Add a neutral WebExtension API adapter that uses Firefox browser.* or Chromium chrome.* without mutating globals.
- Switch extension runtime code to the adapter and add Firefox-specific typings for tabs, windows, tab groups, storage, scripting, and native messaging ports.
- Fix Firefox temporary add-on instructions to load the packaged manifest with background.scripts instead of the Chromium service worker manifest.
- Detect Firefox in clients.list via runtime.getBrowserInfo and keep Chromium user-agent fallback support.
- Make navigate.open wait briefly for Firefox to replace initial about:blank with the requested URL.
- Add JS coverage for API selection, clients.list browser detection, and Firefox navigate.open URL polling.
- Bump package and extension version to 0.15.2.

extension/test/clients.test.ts

@@ -0,0 +1,86 @@
+// @ts-nocheck
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { SessionCommands } from '../src/commands/session';
+import { JobManager } from '../src/classes/JobManager';
+import { makeChromeMock } from './chrome-mock';
+
+function makeSessionCommands() {
+  return new SessionCommands({ jobs: new JobManager() });
+}
+
+test('clients.list uses Firefox runtime.getBrowserInfo when available', async () => {
+  const originalChrome = globalThis.chrome;
+  const originalBrowser = globalThis.browser;
+  const originalNavigator = globalThis.navigator;
+  const chromeMock = makeChromeMock();
+
+  try {
+    delete globalThis.chrome;
+    globalThis.browser = {
+      ...chromeMock,
+      runtime: {
+        getManifest: () => ({ version: '0.15.1' }),
+        getBrowserInfo: async () => ({ name: 'Firefox', vendor: 'Mozilla', version: '149.0', buildID: 'test' }),
+      },
+    };
+    Object.defineProperty(globalThis, 'navigator', {
+      value: { platform: 'test-platform', userAgent: 'Mozilla/5.0 Firefox/149.0' },
+      configurable: true,
+    });
+
+    const clients = await makeSessionCommands().commands['clients.list']({});
+
+    assert.equal(clients[0].name, 'Firefox');
+    assert.equal(clients[0].version, '149.0');
+    assert.equal(clients[0].extensionVersion, '0.15.1');
+  } finally {
+    if (originalChrome === undefined) delete globalThis.chrome;
+    else globalThis.chrome = originalChrome;
+
+    if (originalBrowser === undefined) delete globalThis.browser;
+    else globalThis.browser = originalBrowser;
+
+    Object.defineProperty(globalThis, 'navigator', {
+      value: originalNavigator,
+      configurable: true,
+    });
+  }
+});
+
+test('clients.list falls back to Chromium user-agent when getBrowserInfo is missing', async () => {
+  const originalChrome = globalThis.chrome;
+  const originalBrowser = globalThis.browser;
+  const originalNavigator = globalThis.navigator;
+  const chromeMock = makeChromeMock();
+
+  try {
+    delete globalThis.browser;
+    globalThis.chrome = {
+      ...chromeMock,
+      runtime: {
+        getManifest: () => ({ version: '0.15.1' }),
+      },
+    };
+    Object.defineProperty(globalThis, 'navigator', {
+      value: { platform: 'test-platform', userAgent: 'Mozilla/5.0 Chrome/149.0.0.0 Safari/537.36' },
+      configurable: true,
+    });
+
+    const clients = await makeSessionCommands().commands['clients.list']({});
+
+    assert.equal(clients[0].name, 'Chrome');
+    assert.equal(clients[0].version, '149.0.0.0');
+  } finally {
+    if (originalChrome === undefined) delete globalThis.chrome;
+    else globalThis.chrome = originalChrome;
+
+    if (originalBrowser === undefined) delete globalThis.browser;
+    else globalThis.browser = originalBrowser;
+
+    Object.defineProperty(globalThis, 'navigator', {
+      value: originalNavigator,
+      configurable: true,
+    });
+  }
+});