Add persistent player stats and DB support

Introduce MySQL persistence and an in-memory stats system with async saving.

- Add HikariCP & MySQL connector dependencies and relocate libs in build.gradle.kts.
- Add DatabaseManager (HikariCP) to manage connection pool and lifecycle.
- Add PlayerStats data model and PlayerStatsRepository for table creation, reads, upserts and batch upserts (with prepared statements).
- Add StatsManager: coroutine-based cache, dirty-flags, async batch saves, auto-save (every 5 minutes), load/save APIs and shutdown save.
- Add StatsListener: load on AsyncPlayerPreLoginEvent and save on PlayerQuitEvent.
- Wire DB and stats into main plugin: connect on enable (disable plugin on fail), initialize StatsManager, save/disconnect on disable, register leaderboard command and stats listener.
- Update GameManager to record kills/wins/deaths and adjust scrimScore on events.
- Add LeaderboardCommand and language entries for leaderboard output; expose command in plugin.yml.
- Add database configuration section to config.yml.
- Minor refactor: KitCommand plugin accessor changed to a getter.

These changes provide a robust, pooled DB connection and efficient stats persistence (batched/upserted) to reduce DB load and ensure data safety during shutdown.

src/main/resources/config.yml

@@ -18,4 +18,16 @@ anti-runner:
   punish-time: 25
   # Einstellungen für die Cave-Erkennung
   ignore-vertical-distance: 15.0 # Wenn Höhenunterschied > 15, Timer ignorieren
-  ignore-cave-surface-mix: true  # Ignorieren, wenn einer Sonne hat und der andere nicht
+  ignore-cave-surface-mix: true  # Ignorieren, wenn einer Sonne hat und der andere nicht
+
+database:
+  host: "localhost"
+  port: 3306
+  name: "speedhg"
+  username: "speedhg_user"
+  password: "dein_sicheres_passwort"
+  use-ssl: false   # auf true setzen wenn der DB-Server ein SSL-Zertifikat hat
+
+  pool:
+    max-size: 10   # maximale gleichzeitige Connections (für 1 Server: 5-10 reichen)
+    min-idle: 2    # Mindestanzahl idle Connections im Pool