Add Phase 0: sign-up, login, and profile

- Next.js (App Router) + TypeScript + Tailwind
- Prisma + SQLite for the User model
- Sign-up with 18+ age gate, email/password validation (zod), bcrypt hashing
- Login via NextAuth credentials provider, JWT sessions
- Protected /profile route (view + edit name/bio)

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VL5YUEf2B9LG4xdVUQwcSg

.gitignore

@@ -0,0 +1,26 @@
+# dependencies
+/node_modules
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# env files (never commit secrets)
+.env
+.env*.local
+
+# database
+/prisma/dev.db
+/prisma/dev.db-journal
+
+# misc
+.DS_Store
+*.pem
+npm-debug.log*
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts