feat: user auth, API keys, Stripe billing, and dashboard scoping

- NextAuth v5 credentials auth with registration/login pages
- API key CRUD (create, list, revoke) with secure hashing
- Stripe checkout, webhooks, and customer portal integration
- Rate limiting per subscription tier
- All dashboard API endpoints scoped to authenticated user
- Prisma schema: User, Account, Session, ApiKey, plus Stripe fields
- Auth middleware protecting dashboard and API routes

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-Claude)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

apps/web/src/auth.config.ts

@@ -0,0 +1,9 @@
+import type { NextAuthConfig } from "next-auth";
+
+export default {
+  providers: [],
+  session: { strategy: "jwt" },
+  pages: {
+    signIn: "/login",
+  },
+} satisfies NextAuthConfig;