feat(clients): scaffold mobile (Capacitor) + desktop (Electron) shells

Plan + decisions in CLIENTS.md (parallel mobile+desktop; desktop = technician
client + existing remote-control agent host; mobile = Capacitor wrap).

- desktop/: Electron technician client — loads the live Connect UI, native
  screen capture via setDisplayMediaRequestHandler, persisted session, external
  links to browser; electron-builder config for Win/Mac/Linux installers.
- mobile/: Capacitor project — server.url loads Connect UI, push/camera/status-bar
  plugins declared, www splash fallback; iOS/Android added via `cap add`.
- Reuses the existing /api/v1 + Bearer auth backend; no web-code changes.
- .gitignore: ignore generated mobile/android, mobile/ios platform dirs.

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

.gitignore

@@ -29,6 +29,10 @@ dist/
 build/
 out/
 
+# Native client generated/build artifacts (Capacitor adds platform dirs; Electron builds to dist)
+mobile/android/
+mobile/ios/
+
 # Runtime media (created at startup by config.js)
 server/recordings/
 server/transcripts/