Complete architecture simplification: 54+ files → 37 files

- Removed 11 duplicate router files (auth.py, users.py, decks.py, card_router.py, interactions.py, user_data.py, rooms.py, games/router.py, refresh.py, card_import.py, ws.py)
- Removed duplicate core files (logging_config.py, settings.py)
- Removed unused services (card_mirror_service.py, mtgjson_loader.py, mtgjson_uploader.py)
- Removed unused schemas (proto_messages.py, protocol_constants.py)
- Created run.py startup script for simple execution
- Created app/core/config.py for unified configuration management
- Created app/core/logging.py for logging configuration
- Consolidated routers into 6 focused files (auth_router.py, users_router.py, decks_router.py, cards_router.py, user_data_router.py, games_router.py)
- Updated all imports to use consolidated model paths
- Added backward compatibility aliases in database.py
- Created SIMPLIFICATION_SUMMARY.md documentation

Architecture improvements:
- Single unified database engine with auto-detection (SQLite/PostgreSQL)
- Consolidated models into 2 files (models.py, mtg_models.py)
- Clean router structure with one file per domain
- Simplified configuration with sensible defaults
- SQLite by default for development, PostgreSQL for production

Testing:
- All imports verified working
- App loads successfully
- Ready for development and testing

backend/app/schemas/__init__.py

@@ -65,15 +65,6 @@ from app.schemas.mtg_card_schemas import (
     MtgSetResponse, MtgCardMirrorResponse,
     DeckCardLinkResponse as DeckCardLinkResponseV2, DeckWithCardsResponse as DeckWithCardsResponseV2,
 )
-from app.schemas.proto_messages import (
-    ProtoMessageBase, SessionCommand, GameCommand, GameEvent, Response,
-    ServerInfoUser, ServerInfoDeckStorageFile, ServerInfoDeckStorageFolder,
-    ServerInfoDeckStorageTreeItem, ServerInfoCard, ServerInfoZone, ServerInfoGame,
-)
-from app.schemas.protocol_constants import (
-    SessionCommandType, GameCommandType, GameEventType, ResponseCode,
-    ZoneType, UserLevelFlag,
-)
 
 __all__ = [
     # Auth
@@ -137,11 +128,4 @@ __all__ = [
     "MtgCardResponse", "MtgCardSearchRequest", "MtgCardSearchResponse",
     "MtgSetResponse", "MtgCardMirrorResponse",
     "DeckCardLinkResponseV2", "DeckWithCardsResponseV2",
-    # Proto Messages
-    "ProtoMessageBase", "SessionCommand", "GameCommand", "GameEvent", "Response",
-    "ServerInfoUser", "ServerInfoDeckStorageFile", "ServerInfoDeckStorageFolder",
-    "ServerInfoDeckStorageTreeItem", "ServerInfoCard", "ServerInfoZone", "ServerInfoGame",
-    # Protocol Constants
-    "SessionCommandType", "GameCommandType", "GameEventType", "ResponseCode",
-    "ZoneType", "UserLevelFlag",
 ]