implemented optional authentification app and stricter password and user rules.

Also against brute force.

database_setup.sql

@@ -1,16 +1,28 @@
 CREATE TABLE users (
-    id INT AUTO_INCREMENT PRIMARY KEY,
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
     username VARCHAR(20) NOT NULL UNIQUE,
-    password VARCHAR(80) NOT NULL,
-    email VARCHAR(120) NOT NULL UNIQUE,
-    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+    password VARCHAR(255) NOT NULL,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    last_login DATETIME,
+    two_factor_enabled BOOLEAN NOT NULL DEFAULT 0,
+    two_factor_secret VARCHAR(64)
+);
+
+CREATE TABLE login_attempts (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    ip_address VARCHAR(45) NOT NULL,
+    username VARCHAR(80) NOT NULL,
+    failed_attempts INTEGER NOT NULL DEFAULT 0,
+    locked_until DATETIME,
+    last_failed_at DATETIME,
+    CONSTRAINT uq_login_attempt_ip_username UNIQUE (ip_address, username)
 );
 
 CREATE TABLE game_state (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
     user_id INTEGER NOT NULL,
-    board TEXT NOT NULL,             -- JSON String (z.B. "[0,4,7,5,2,6,1,3]")
-    mode TEXT NOT NULL,              -- "queens" oder "rooks"
+    board TEXT NOT NULL,
+    mode TEXT NOT NULL,
     board_size INTEGER NOT NULL DEFAULT 8,
     save_name VARCHAR(80) NOT NULL DEFAULT 'Unnamed Save',
     save_note TEXT NOT NULL DEFAULT '',