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.ts

@@ -0,0 +1,72 @@
+import NextAuth from "next-auth";
+import Credentials from "next-auth/providers/credentials";
+import { compare } from "bcryptjs";
+import { z } from "zod";
+import { prisma } from "@/lib/prisma";
+import authConfig from "./auth.config";
+
+declare module "next-auth" {
+  interface Session {
+    user: {
+      id: string;
+      email: string;
+      name?: string | null;
+      image?: string | null;
+    };
+  }
+}
+
+declare module "@auth/core/jwt" {
+  interface JWT {
+    id: string;
+  }
+}
+
+const loginSchema = z.object({
+  email: z.email("Invalid email address"),
+  password: z.string().min(8, "Password must be at least 8 characters"),
+});
+
+export const { handlers, auth, signIn, signOut } = NextAuth({
+  ...authConfig,
+  providers: [
+    Credentials({
+      credentials: {
+        email: { label: "Email", type: "email" },
+        password: { label: "Password", type: "password" },
+      },
+      async authorize(credentials) {
+        const parsed = loginSchema.safeParse(credentials);
+        if (!parsed.success) return null;
+
+        const { email, password } = parsed.data;
+
+        const user = await prisma.user.findUnique({
+          where: { email: email.toLowerCase() },
+        });
+        if (!user) return null;
+
+        const isValid = await compare(password, user.passwordHash);
+        if (!isValid) return null;
+
+        return {
+          id: user.id,
+          email: user.email,
+          name: user.name,
+        };
+      },
+    }),
+  ],
+  callbacks: {
+    jwt({ token, user }) {
+      if (user) {
+        token.id = user.id as string;
+      }
+      return token;
+    },
+    session({ session, token }) {
+      session.user.id = token.id;
+      return session;
+    },
+  },
+});