🚀 Backend komplett implementiert

Features:
- Auth mit JWT + Argon2 (Login, Register, Refresh)
- Rollen-System (Chef/Disponent/Mitarbeiter)
- User Management mit Berechtigungen
- Aufträge mit Zuweisungen
- Verfügbarkeitsplanung
- Stundenzettel mit Foto-Upload Support
- Modulares System mit Config
- Entwickler-Panel Endpoints

Tech:
- Deno + Oak
- PostgreSQL
- CORS enabled

src/db/postgres.ts

@@ -0,0 +1,54 @@
+import { Pool } from "https://deno.land/x/postgres@v0.17.0/mod.ts";
+
+const DATABASE_URL = Deno.env.get("DATABASE_URL") || 
+  "postgres://secu:SeCu2026!SecureDB@localhost:5434/secu";
+
+let pool: Pool;
+
+export async function initDB(): Promise<void> {
+  pool = new Pool(DATABASE_URL, 10);
+  
+  // Test connection
+  const client = await pool.connect();
+  try {
+    const result = await client.queryObject`SELECT NOW()`;
+    console.log("✅ Database connected:", result.rows[0]);
+  } finally {
+    client.release();
+  }
+}
+
+export function getPool(): Pool {
+  return pool;
+}
+
+export async function query<T>(sql: string, params?: unknown[]): Promise<T[]> {
+  const client = await pool.connect();
+  try {
+    const result = await client.queryObject<T>({
+      text: sql,
+      args: params || [],
+    });
+    return result.rows;
+  } finally {
+    client.release();
+  }
+}
+
+export async function queryOne<T>(sql: string, params?: unknown[]): Promise<T | null> {
+  const rows = await query<T>(sql, params);
+  return rows[0] || null;
+}
+
+export async function execute(sql: string, params?: unknown[]): Promise<number> {
+  const client = await pool.connect();
+  try {
+    const result = await client.queryObject({
+      text: sql,
+      args: params || [],
+    });
+    return result.rowCount || 0;
+  } finally {
+    client.release();
+  }
+}