fix: Load admin credentials from .env file

- Add dotenv dependency and load .env configuration in auth.ts
- Admin credentials now read from environment variables:
  - ADMIN_USERNAME (default: owner)
  - ADMIN_PASSWORD_HASH (default: admin123 hash)
  - ADMIN_EMAIL (default: owner@stargirlnails.de)
- Remove hardcoded admin credentials
- Add fallback values for backward compatibility
- Clear existing user storage to force recreation with new credentials

src/server/rpc/auth.ts

@@ -2,6 +2,10 @@ import { call, os } from "@orpc/server";
 import { z } from "zod";
 import { randomUUID } from "crypto";
 import { createKV } from "@/server/lib/create-kv";
+import { config } from "dotenv";
+
+// Load environment variables from .env file
+config();
 
 const UserSchema = z.object({
   id: z.string(),