Sessions leave redacted logs; viewers wait for a member relay's source before opening it

Logs: one redaction pass (query strings to names, member tokens,
passwords, cookies, auth headers) for every line; daily files with size
and age caps in the app (hosted server included) and the dedicated
server (--log-dir); swaps, relay channels, per-member /r /m /j outcomes,
server fetches, mpv load errors, yt-dlp runs. Settings > About: Copy
diagnostics, Open logs folder.

Bilibili through someone else: the viewer opened /r/ before the source
dialled in; the server holds that request and mpv gives up after 5 s
("could not be opened"). Viewers now open a member relay once it is
live, the putter starts its source before its own player, and track
sizes are read in parallel.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/desktop/lib/main.dart

@@ -9,6 +9,7 @@ import 'package:window_manager/window_manager.dart';
 
 import 'app.dart';
 import 'src/playback/yt_dlp_app.dart';
+import 'src/platform/app_log.dart';
 import 'src/platform/desktop_entry.dart';
 import 'src/platform/window_memory.dart';
 import 'src/screens/home/ui.dart';
@@ -41,6 +42,7 @@ Future<void> main(List<String> args) async {
         ),
       );
   WidgetsFlutterBinding.ensureInitialized();
+  await startAppLogging();
   await Hive.initFlutter();
   await AppSettings.instance.ensureLoaded();
   await windowManager.ensureInitialized();