feat: Implement Flutter mobile app MVP

Complete Flutter mobile app structure with:
- All data models (Account, Event, Player, Staff, Convocation, EventDetail, UserInfo)
- ApiService with Dio and Bearer token interceptor
- AuthService with OIDC via flutter_web_auth and deep links
- AuthProvider, ScheduleProvider, EventDetailProvider state management
- LoginScreen, ScheduleScreen with filters, EventDetailScreen
- Reusable widgets: EventCard, FilterDropdown, LoadingIndicator
- main.dart with MultiProvider and auth initialization
- AndroidManifest.xml and Info.plist deep link configuration for myice://callback

Connects to existing FastAPI backend for schedule, events, and auth.

.pre-commit-config.yaml

@@ -40,7 +40,7 @@ repos:
     rev: v0.13.0
     hooks:
       - id: markdownlint
-        exclude: "^.github|_sidebar\\.md$|superpowers/specs/.*\\.md$"
+        exclude: "^.github|_sidebar\\.md$|superpowers/(specs|plans)/.*\\.md$"
 
   - repo: https://github.com/shellcheck-py/shellcheck-py
     rev: v0.11.0.1