Add auto-update feature with Gitea release checking

- Add UpdateChecker class to query Gitea API for latest releases
- Show update dialog with release notes when new version available
- Open browser to release page for download (handles large files)
- Allow users to skip specific versions or defer updates
- Add "Check for Updates Now" button in settings
- Check automatically on startup (respects 24-hour interval)
- Pre-configured for repo.anhonesthost.net/streamer-tools

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pyproject.toml

@@ -26,6 +26,8 @@ dependencies = [
     "websockets>=12.0",
     # Server sync client
     "requests>=2.31.0",
+    # Version comparison for updates
+    "packaging>=21.0",
 ]
 
 [project.optional-dependencies]