Broaden PO-token capture (initplayback / any googlevideo request with pot=)

Verified end-to-end by loading the real extension into headless Chromium (Playwright):
content_hook captures the gvs pot via the fetch/XHR hook, bridges it to session storage,
and fillSpaceFields populates the Space fields with input events. Broaden the URL matcher
beyond /videoplayback to also catch /initplayback and any googlevideo.com request carrying
a pot param.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

extension/background.js

@@ -13,7 +13,8 @@ const FILTER = { urls: ["*://*.googlevideo.com/*"] };
 chrome.webRequest.onBeforeRequest.addListener(
   (details) => {
     try {
-      if (details.url.indexOf("videoplayback") === -1) return;
+      if (details.url.indexOf("videoplayback") === -1 &&
+          details.url.indexOf("initplayback") === -1) return;
       chrome.storage.session.set({ gvAnySeen: true, lastSeen: Date.now() });
       const u = new URL(details.url);
       const pot = u.searchParams.get("pot");

extension/content_hook.js

@@ -12,9 +12,15 @@
 
   function scanUrl(url) {
     try {
-      if (!url || String(url).indexOf("videoplayback") === -1) return;
+      if (!url) return;
+      const s = String(url);
+      if (
+        s.indexOf("videoplayback") === -1 &&
+        s.indexOf("initplayback") === -1 &&
+        s.indexOf("googlevideo.com") === -1
+      ) return;
       report("seen", null);
-      const u = new URL(url, location.href);
+      const u = new URL(s, location.href);
       const pot = u.searchParams.get("pot");
       if (pot) report("pot", { pot: pot, c: u.searchParams.get("c") || "" });
     } catch (e) {}