feat(website): add the phone remote control guide

New guide at /blog/remote-control-guide/: enabling the remote in Settings,
opening it on a phone from the QR code, what each control does and which
list it navigates, a checklist for a page that does not load, and why the
remote must stay on the local network. Eight FAQ entries. The remote-control
feature page now links to it instead of the M3U guide.

Both screenshots are mock-backed. The phone view is the first "browser" shot:
a manifest entry names a loopback URL and a mobile viewport, and the capture
frames it in a separate Chromium page behind the same network and content
guards, with the manifest validator accepting loopback origins only. The
setup saves the remote-control setting so the app's own server answers, then
selects a live channel; the Xtream mock's marketing scenario now serves live
stream URLs from local bytes so that selection never leaves the machine.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tools/testing/website-guides.test.mjs

@@ -50,6 +50,13 @@ const GUIDES = [
       'blog/guides/screenshots/guide-sources-menu-dark.png',
     ],
   },
+  {
+    slug: 'remote-control-guide',
+    screenshots: [
+      'blog/guides/screenshots/guide-remote-settings-dark.png',
+      'blog/guides/screenshots/guide-remote-phone-dark.png',
+    ],
+  },
 ];
 
 const readDist = (relativePath) => readFile(new URL(relativePath, distRoot), 'utf8');