feat: Enhance UgcPurchasablesController to handle bulk requests with object arrays

- Updated Bulk method to parse incoming JSON object arrays for UGC item IDs.
- Introduced ReadBulkIdsAsync to handle both object arrays and flat GUID lists.
- Added synthetic placeholder responses for missing UGC items to prevent client errors.

feat: Implement MatchmakeRoom and MatchmakeSubRoom endpoints in GoToController

- Added MatchmakeRoom and MatchmakeSubRoom methods to facilitate joining public and sub-rooms by numeric ID.
- Enhanced ApplySubRoomMutation to ensure proper state transitions for sub-rooms.
- Improved logging for matchmaking actions.

fix: Refactor PlayerSettingsController to handle database save exceptions

- Introduced SaveSettingsChangesAsync to manage DbUpdateException for busy SQLite scenarios.
- Updated methods to call SaveSettingsChangesAsync instead of direct SaveChangesAsync.

chore: Update URL coverage documentation for new matchmaking endpoints

- Documented new MatchmakeRoom and MatchmakeSubRoom endpoints in url-coverage.md.

chore: Add default room data file for room loading

- Included default_room.room to serve as a fallback for missing room data.

fix: Improve SQLite concurrency handling in DatabaseBootstrap

- Configured SQLite to use WAL mode and set a busy timeout for better concurrency.

chore: Create SqliteErrors utility for handling SQLite exceptions

- Added SqliteErrors class to encapsulate logic for detecting busy SQLite exceptions.

refactor: Update RoomDataBlobService to serve default room data

- Modified GetDefaultBlob to load and serve a default room blob with proper role data.

DorkNet.Server/Startup/DatabaseBootstrap.cs

@@ -1,4 +1,5 @@
 using Microsoft.EntityFrameworkCore;
+using System.Data;
 using DorkNet.Server.Data;
 using DorkNet.Server.Services;
 using Serilog;
@@ -36,6 +37,7 @@ public static class DatabaseBootstrap
 
         if (db.Database.IsSqlite())
         {
+            await ConfigureSqliteForLocalConcurrencyAsync(db);
             BaselineExistingSchemaIfNeeded(db);
             db.Database.Migrate();
         }
@@ -171,6 +173,27 @@ public static class DatabaseBootstrap
         Controllers.Health.HealthController.MigrationsComplete = true;
     }
 
+    private static async Task ConfigureSqliteForLocalConcurrencyAsync(DorkNetDbContext db)
+    {
+        var conn = db.Database.GetDbConnection();
+        var closeAfter = conn.State != ConnectionState.Open;
+        if (closeAfter) await conn.OpenAsync();
+
+        try
+        {
+            await using var cmd = conn.CreateCommand();
+            cmd.CommandText = "PRAGMA journal_mode=WAL;";
+            await cmd.ExecuteScalarAsync();
+
+            cmd.CommandText = "PRAGMA busy_timeout=30000;";
+            await cmd.ExecuteNonQueryAsync();
+        }
+        finally
+        {
+            if (closeAfter) await conn.CloseAsync();
+        }
+    }
+
     /// <summary>Idempotently create the SignupCodes + PendingDevices
     /// tables on whichever provider is in use. Safe to run every boot:
     /// CREATE TABLE / INDEX IF NOT EXISTS no-op once they exist (whether