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/app/docs/python-sdk/page.tsx

@@ -50,7 +50,7 @@ export default function PythonSdkPage() {
       <ApiSection
         name="init()"
         signature="agentlens.init(api_key, endpoint, *, flush_interval=5.0, max_batch_size=100, enabled=True)"
-        description="Initialize the AgentLens SDK. Must be called before any tracing functions. Typically called once at application startup."
+        description="Initialize the AgentLens SDK. Must be called before any tracing functions. Typically called once at application startup. Your API key can be created after registering at agentlens.vectry.tech — go to Dashboard > API Keys to generate one."
       >
         <h4 className="text-sm font-medium text-neutral-300 mb-2">
           Parameters
@@ -70,7 +70,7 @@ export default function PythonSdkPage() {
                 <td className="py-2 pr-4 font-mono text-emerald-400 text-xs">api_key</td>
                 <td className="py-2 pr-4 text-neutral-500">str</td>
                 <td className="py-2 pr-4 text-neutral-500">required</td>
-                <td className="py-2">Your AgentLens API key</td>
+                <td className="py-2">Your AgentLens API key (from <a href="/dashboard/keys" className="text-emerald-400 hover:underline">Dashboard &rarr; API Keys</a>)</td>
               </tr>
               <tr className="border-b border-neutral-800/50">
                 <td className="py-2 pr-4 font-mono text-emerald-400 text-xs">endpoint</td>