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/app/Support/Database.php

@@ -5,15 +5,17 @@ declare(strict_types=1);
 namespace App\Support;
 
 use PDO;
+use PDOException;
 
 final class Database
 {
-    private static string $path;
     private static ?PDO $connection = null;
+    private static array $config = [];
 
-    public static function configure(string $path): void
+    public static function configure(array $config): void
     {
-        self::$path = $path;
+        self::$config = $config;
+        self::$connection = null; // reset on reconfigure
     }
 
     public static function connection(): PDO
@@ -22,16 +24,43 @@ final class Database
             return self::$connection;
         }
 
-        $directory = dirname(self::$path);
-        if (!is_dir($directory)) {
-            mkdir($directory, 0775, true);
+        $driver = self::$config['db_driver'] ?? 'sqlite';
+
+        if ($driver === 'pgsql') {
+            $host = self::$config['db_host'] ?? '127.0.0.1';
+            $port = self::$config['db_port'] ?? '5432';
+            $dbname = self::$config['db_database'] ?? '';
+            $user = self::$config['db_username'] ?? '';
+            $password = self::$config['db_password'] ?? '';
+
+            $dsn = "pgsql:host={$host};port={$port};dbname={$dbname}";
+            self::$connection = new PDO($dsn, $user, $password);
+        } else {
+            $path = self::$config['db_path'] ?? self::$config['db_path'] ?? '';
+            $directory = dirname($path);
+            if (!is_dir($directory)) {
+                mkdir($directory, 0775, true);
+            }
+            self::$connection = new PDO('sqlite:' . $path);
+            self::$connection->exec('PRAGMA foreign_keys = ON');
         }
 
-        self::$connection = new PDO('sqlite:' . self::$path);
         self::$connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
         self::$connection->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
-        self::$connection->exec('PRAGMA foreign_keys = ON');
 
         return self::$connection;
     }
+
+    public static function isPostgres(): bool
+    {
+        return (self::$config['db_driver'] ?? 'sqlite') === 'pgsql';
+    }
+
+    public static function lastInsertId(): string
+    {
+        if (self::isPostgres()) {
+            return self::$connection->query('SELECT lastval()')->fetchColumn();
+        }
+        return self::$connection->lastInsertId();
+    }
 }