Add Phase 1 critical endpoints: Config & Save/Load system

- Added ConfigController with 4 endpoints:
  - getGameConfig: Server config, feature flags, URLs
  - getServerTime: UTC timestamps
  - getFeatureFlags: Feature toggles
  - getServerStatus: Health check

- Added save/load system to ProgressionController:
  - POST /save/{synergyId}: Save JSON blob
  - GET /save/{synergyId}/load: Load JSON blob
  - Version tracking and timestamps

- Added PlayerSave entity to database:
  - Stores arbitrary JSON game state
  - Version tracking (increments on save)
  - LastModified timestamps

- Updated appsettings.json:
  - ServerSettings section (version, URLs, MOTD)
  - FeatureFlags section (7 feature toggles)

- Created migration: AddPlayerSavesAndConfig
- Updated ApiModels with new DTOs
- All endpoints tested and working

Phase 1 objectives complete:
✅ Synergy ID generation (already existed)
✅ Configuration endpoints (new)
✅ Save/load system (new)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

RR3CommunityServer/bin/Debug/net8.0/appsettings.json

@@ -23,6 +23,24 @@
     "UnlimitedCurrency": false,
     "EnableModding": true,
     "MaxCustomCarUploadSizeMB": 100,
-    "MaxCustomTrackUploadSizeMB": 200
+    "MaxCustomTrackUploadSizeMB": 200,
+    "Version": "1.0.0",
+    "GameVersion": "14.0.1",
+    "MaintenanceMode": false,
+    "MessageOfTheDay": "Welcome to RR3 Community Server! 🏁",
+    "BaseUrl": "http://localhost:5001",
+    "AssetsUrl": "http://localhost:5001/content/api",
+    "LeaderboardsUrl": "http://localhost:5001/leaderboards/api",
+    "MultiplayerUrl": "http://localhost:5001/multiplayer/api"
+  },
+  "FeatureFlags": {
+    "MultiplayerEnabled": false,
+    "LeaderboardsEnabled": true,
+    "DailyRewardsEnabled": true,
+    "TimeTrialsEnabled": true,
+    "CustomContentEnabled": true,
+    "SpecialEventsEnabled": true,
+    "AllItemsFree": true
   }
 }
+