Add Authentik OIDC integration (task 06)

- next-auth@beta + @auth/drizzle-adapter wired up with database sessions
- src/lib/auth.ts: OIDC provider, authorized callback, signIn household-attach, getCurrentUser()
- src/middleware.ts: protects all routes except /login, /s/*, /api/auth/*
- src/app/api/auth/[...nextauth]/route.ts: mounts Auth.js handlers
- src/app/login/page.tsx: single SSO sign-in button (server action)
- Schema: users extended (name/emailVerified/image), accounts/sessions/verificationTokens added
- drizzle/0001_auth_tables.sql: migration for schema changes
- deploy/authentik/README.md: manual bootstrap steps for Authentik
- src/lib/db.ts: pass schema to drizzle for relational query builder

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/middleware.ts

@@ -0,0 +1,8 @@
+export { auth as middleware } from "@/lib/auth";
+
+export const config = {
+  matcher: [
+    // Skip Next.js internals and static files
+    "/((?!_next/static|_next/image|favicon.ico).*)",
+  ],
+};