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/Models/ApiModels.cs

@@ -130,3 +130,75 @@ public class DirectorResponse
     public string environment { get; set; } = "COMMUNITY";
     public string version { get; set; } = "1.0.0";
 }
+
+// Configuration models
+public class GameConfig
+{
+    public long ServerTime { get; set; }
+    public string ServerVersion { get; set; } = string.Empty;
+    public string GameVersion { get; set; } = string.Empty;
+    public bool MaintenanceMode { get; set; }
+    public string MessageOfTheDay { get; set; } = string.Empty;
+    public FeatureFlags FeatureFlags { get; set; } = new();
+    public ServerUrls Urls { get; set; } = new();
+}
+
+public class FeatureFlags
+{
+    public bool MultiplayerEnabled { get; set; }
+    public bool LeaderboardsEnabled { get; set; }
+    public bool DailyRewardsEnabled { get; set; }
+    public bool TimeTrialsEnabled { get; set; }
+    public bool CustomContentEnabled { get; set; }
+    public bool SpecialEventsEnabled { get; set; }
+    public bool AllItemsFree { get; set; }
+}
+
+public class ServerUrls
+{
+    public string BaseUrl { get; set; } = string.Empty;
+    public string AssetsUrl { get; set; } = string.Empty;
+    public string LeaderboardsUrl { get; set; } = string.Empty;
+    public string MultiplayerUrl { get; set; } = string.Empty;
+}
+
+public class ServerTime
+{
+    public long ServerTimestamp { get; set; }
+    public long ServerTimeMs { get; set; }
+    public string Timezone { get; set; } = "UTC";
+    public bool IsDST { get; set; }
+}
+
+public class ServerStatus
+{
+    public string Status { get; set; } = "online";
+    public string Version { get; set; } = string.Empty;
+    public bool MaintenanceMode { get; set; }
+    public int PlayerCount { get; set; }
+    public long Uptime { get; set; }
+    public string Message { get; set; } = string.Empty;
+}
+
+// Save/Load models
+public class PlayerSaveData
+{
+    public string SynergyId { get; set; } = string.Empty;
+    public string SaveDataJson { get; set; } = string.Empty;
+    public long Version { get; set; } = 1;
+    public long LastModified { get; set; }
+}
+
+public class SaveDataRequest
+{
+    public string SynergyId { get; set; } = string.Empty;
+    public string SaveData { get; set; } = string.Empty;
+}
+
+public class SaveDataResponse
+{
+    public string SaveData { get; set; } = string.Empty;
+    public long Version { get; set; }
+    public long LastModified { get; set; }
+    public bool Success { get; set; }
+}