Implement Node.js backend rewrite with SQLite authentication, admin dashboard and One-Click docker update

backend/database.js

@@ -0,0 +1,35 @@
+const sqlite3 = require('sqlite3').verbose();
+const path = require('path');
+const bcrypt = require('bcryptjs');
+
+const dbPath = process.env.DB_PATH || path.join(__dirname, '../data/database.sqlite');
+const db = new sqlite3.Database(dbPath);
+
+console.log('Using database at', dbPath);
+
+db.serialize(() => {
+    db.run(`CREATE TABLE IF NOT EXISTS users (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        username TEXT UNIQUE NOT NULL,
+        password_hash TEXT NOT NULL,
+        role TEXT NOT NULL
+    )`);
+
+    db.run(`CREATE TABLE IF NOT EXISTS user_images (
+        user_id INTEGER,
+        image_name TEXT,
+        FOREIGN KEY(user_id) REFERENCES users(id),
+        UNIQUE(user_id, image_name)
+    )`);
+
+    // Create default admin user if none exists
+    db.get('SELECT * FROM users WHERE username = ?', ['admin'], (err, row) => {
+        if (!row) {
+            const hash = bcrypt.hashSync('admin123', 10);
+            db.run('INSERT INTO users (username, password_hash, role) VALUES (?, ?, ?)', ['admin', hash, 'admin']);
+            console.log('Default admin created with credentials: admin / admin123');
+        }
+    });
+});
+
+module.exports = db;