feat: v0.3.0 — history, 4-button search, options page, newtab override

Web Store submission target. Mirrors rangerhq-radio's track-history pattern
(inc/history.php) so the family stays coherent across surfaces.

Highlights
- New Tab Page override (Tier 2.5) — Chrome's default new tab replaced with
  a RangerHQ-branded landing showing the player, current track, quick chips,
  searchable browse list, and now history + favourites tabs.
- Track history + favourites — capped FIFO 500, dedup against last entry,
  skip "(unknown)" artist (SomaFM dead-air). Stored in chrome.storage.local
  under tuner.history + tuner.favourites.
- 4-button search per entry — Spotify / YouTube / Apple Music / Bandcamp.
  Pure public-search-URL link-outs in a new tab, NO auth, NO API keys, NO
  quota, NO third-party SDK embedded.
- Options page (chrome://extensions → details → options) — live stats,
  history cap slider (50-500), Clear history / Clear favourites / Clear
  EVERYTHING buttons, About panel with Gitea + davidtkeane.com links.
- Popup nav row — Open in tab / History (#hash deep link) / Settings,
  using chrome.tabs.create + chrome.runtime.openOptionsPage. No new perms.
- Cross-surface sync — popup ↔ newtab listen on chrome.storage.onChanged
  for tuner.currentStationId / tuner.isPlaying / history / favourites.
- Storage gateway — offscreen doc can't reliably reach chrome.storage in
  some Chrome versions, so it sends LOG_TRACK_REQUEST to the SW which
  does the write. history.js also defensively guards every storage call.
- Metadata latency fix — polling now starts immediately on PLAY, in
  parallel with audio buffer fill. First track display drops from
  ~10-15s to ~1-2s.

Permissions unchanged
- Still ["offscreen", "storage"] + somafm.com host only.
- chrome.tabs.create works on our own extension URLs without "tabs" perm.
- No webRequest, no <all_urls>, no third-party SDK.

Bumped from 0.1.0 (last tag on Gitea) directly to 0.3.0.
v0.2.0 (newtab + clock) was a working local build but never tagged;
its features ship together with v0.3.0 in this single commit.

src/background/service-worker.js

@@ -1,7 +1,12 @@
 // RangerHQ Tuner — Service Worker.
 // Job: open the offscreen audio document on demand and route messages
-// between the popup (UI) and the offscreen document (audio engine).
-// We hold no state here — Chrome will kill this worker at any time.
+// between the popup/newtab (UI) and the offscreen document (audio engine).
+// Also acts as the storage gateway for the offscreen doc — offscreen
+// docs don't reliably have chrome.storage, so they message us instead.
+// We hold no in-memory state here — Chrome will kill this worker at any time.
+
+import { TARGETS, TYPES } from '../lib/messages.js';
+import { logTrack } from '../lib/history.js';
 
 const OFFSCREEN_PATH = 'src/offscreen/offscreen.html';
 
@@ -19,15 +24,29 @@ async function ensureOffscreen() {
 
 chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {
   // Only react to messages targeted at the service worker.
-  if (msg.target !== 'sw') return;
+  if (msg.target !== TARGETS.SW) return;
 
   (async () => {
     try {
+      // Storage-gateway path: write to chrome.storage on behalf of the
+      // offscreen document, which can't always reach it directly.
+      if (msg.type === TYPES.LOG_TRACK_REQUEST) {
+        const appended = await logTrack(msg.entry || {});
+        if (appended) {
+          chrome.runtime.sendMessage({
+            target: TARGETS.POPUP,
+            type:   TYPES.TRACK_LOGGED,
+          }).catch(() => {}); // no UI listening is fine
+        }
+        sendResponse({ ok: true, appended });
+        return;
+      }
+
+      // Default: forward audio-control messages to the offscreen doc.
       await ensureOffscreen();
-      // Re-route the message to the offscreen document.
       const response = await chrome.runtime.sendMessage({
         ...msg,
-        target: 'offscreen',
+        target: TARGETS.OFFSCREEN,
       });
       sendResponse(response);
     } catch (err) {