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/src/classes/JobManager.ts

@@ -1,7 +1,8 @@
+import { webExtApi as api } from '../browser-api';
 /**
  * Background-job retention helpers + the JobManager that owns the live job map.
  *
- * `pruneFinishedJobs` / `MAX_FINISHED_JOBS` are kept free of chrome.* /
+ * `pruneFinishedJobs` / `MAX_FINISHED_JOBS` are kept free of api.* /
  * service-worker side effects so the retention logic (memory-leak guard) can be
  * unit-tested in isolation.
  */
@@ -16,7 +17,7 @@ export const MAX_FINISHED_JOBS = 20;
 
 // Watchdog: if a runner never resolves/rejects (e.g. executeScript against a
 // dead tab), finalize the job as an error so its persist interval stops instead
-// of writing to chrome.storage.local every second forever.
+// of writing to api.storage.local every second forever.
 export const JOB_TIMEOUT_MS = 5 * 60 * 1000;
 
 /**
@@ -65,11 +66,11 @@ export class JobManager {
     const running = all.filter(job => job.status === "running");
     const finished = all.filter(job => job.status !== "running").slice(-MAX_FINISHED_JOBS);
     const recentJobs = [...running, ...finished].map(({ __timer, __watchdog, ...rest }) => rest);
-    await chrome.storage.local.set({ recentJobs });
+    await api.storage.local.set({ recentJobs });
   }
 
   // Evict the oldest finished jobs once their count exceeds the retention cap.
-  // Recent finished jobs remain queryable via chrome.storage.local (persistJobs)
+  // Recent finished jobs remain queryable via api.storage.local (persistJobs)
   // even after eviction from the in-memory Map.
   private pruneJobs() {
     pruneFinishedJobs(this.jobs, MAX_FINISHED_JOBS);
@@ -143,7 +144,7 @@ export class JobManager {
   async status({ jobId }: { jobId?: string }) {
     const job = this.jobs.get(jobId);
     if (job) return { ...job };
-    const { recentJobs } = await chrome.storage.local.get<{ recentJobs?: Job[] }>("recentJobs");
+    const { recentJobs } = await api.storage.local.get<{ recentJobs?: Job[] }>("recentJobs");
     const stored = (recentJobs || []).find(entry => entry.id === jobId);
     if (!stored) throw new Error(`Job '${jobId}' not found`);
     return stored;