DatabaseManager: exec, run und transaction Methoden ergaenzt

Generische Hilfsmethoden fuer Schema-Operationen (exec),
parametrisierte Writes (run) und Transaktionen (transaction).

Co-Authored-By: tolvitty <noreply@anthropic.com>

src/core/database.ts

@@ -262,6 +262,18 @@ export class DatabaseManager {
     return stmt.all(...params);
   }
 
+  exec(sql: string): void {
+    this.db.exec(sql);
+  }
+
+  run(sql: string, ...params: unknown[]): void {
+    this.db.prepare(sql).run(...params);
+  }
+
+  transaction<T>(fn: () => T): T {
+    return this.db.transaction(fn)();
+  }
+
   // ---------------------------------------------------------------------------
   // Retention & Maintenance
   // ---------------------------------------------------------------------------