Split API and frontend, migrate SQLite to PostgreSQL

- api.fahrschultermin.de: full API entry point with CORS + session auth
- fahrschultermin.de: frontend only, no more /api/v1 routing
- Database.php: PostgreSQL support (pgsql driver + lastval())
- All repositories: use Database::lastInsertId() for PG compatibility
- config/app.php: PostgreSQL connection settings + CORS config
- bootstrap.php: pass full $config to Database::configure()
- public/index.php: fetch-patch to redirect /api/v1 to api.fahrschultermin.de
- database/schema_pgsql.sql: full PostgreSQL schema (BIGSERIAL)
- database/import_pgsql.sql: 518 rows migrated from SQLite

www/fahrschultermin.de/config/app.php

@@ -4,10 +4,35 @@ declare(strict_types=1);
 
 return [
     'app_name' => 'DriveTime Planner',
-    'env' => 'local',
-    'debug' => true,
+    'env' => 'production',
+    'debug' => false,
+
+    // Database: set db_driver to 'pgsql' or 'sqlite'
+    'db_driver' => 'pgsql',
+    'db_host' => '127.0.0.1',
+    'db_port' => '5433',
+    'db_database' => 'fahrschultermin',
+    'db_username' => 'fahrschultermin_api',
+    'db_password' => 'X9wL3pN7kRtHvMbZs4cGfYu2Dj6qAe8t',
+
+    // Legacy SQLite path (used when db_driver = 'sqlite')
     'db_path' => __DIR__ . '/../storage/database/app.sqlite',
+
+    // Session
     'session_path' => __DIR__ . '/../storage/sessions',
     'session_name' => 'drive_time_session',
+    'session_domain' => '.fahrschultermin.de',
+
+    // API
+    'api_base_url' => 'https://api.fahrschultermin.de',
+    'frontend_url' => 'https://fahrschultermin.de',
+
+    // CORS
+    'cors_allowed_origins' => [
+        'https://fahrschultermin.de',
+        'https://www.fahrschultermin.de',
+    ],
+
+    // Frontend asset path (for fahrschultermin.de frontend)
     'frontend_entry' => __DIR__ . '/../public/assets/index.js',
 ];