feat: PYRAMID_PROFILE_DIR-Override fuer Desktop-Testprofile (app_dirs.dart)

DB, auth_log und Media-Cache laufen jetzt ueber appSupportDir(); nur auf
Desktop und nur wenn PYRAMID_PROFILE_DIR gesetzt ist, landet alles in einem
eigenen Profilverzeichnis - fuer Autopilot-Testlogins parallel zur echten
Session. Ohne Variable exakt das bisherige Verhalten. secure_storage/
shared_preferences bewusst nicht umgeleitet (Begruendung im Dateikopf).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/core/app_database.dart

@@ -5,11 +5,11 @@ import 'dart:math';
 import 'package:flutter/foundation.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'package:path/path.dart' as p;
-import 'package:path_provider/path_provider.dart';
 import 'package:sqflite/sqflite.dart' as sqflite_native;
 import 'package:sqflite_common_ffi/sqflite_ffi.dart';
 import 'package:sqlcipher_flutter_libs/sqlcipher_flutter_libs.dart';
 import 'package:sqlite3/open.dart';
+import 'package:pyramid/core/app_dirs.dart';
 import 'package:pyramid/core/auth_log.dart';
 
 /// Läuft im DB-Isolate der FFI-Factory (muss deshalb top-level sein):
@@ -56,7 +56,7 @@ class AppDatabase {
       !kIsWeb && (Platform.isAndroid || Platform.isWindows || Platform.isLinux);
 
   static Future<String> _dbPath() async {
-    final appDir = await getApplicationSupportDirectory();
+    final appDir = await appSupportDir();
     return p.join(appDir.path, 'pyramid.sqlite');
   }