Add user auth with JWT, switch to bun test

- User table with company_id FK, unique email, role enum
- Register/login routes with bcrypt + JWT token generation
- Auth plugin with authenticate decorator and role guards
- Login uses globally unique email (no company header needed)
- Dev-auth plugin kept as fallback when JWT_SECRET not set
- Switched from vitest to bun:test (vitest had ESM resolution
  issues with zod in Bun's module structure)
- Upgraded to zod 4
- Added Dockerfile.dev and API service to docker-compose
- 8 tests passing (health + auth)

.env.example

@@ -1,10 +1,14 @@
 # Forte — Development Environment Variables
+# These are used inside Docker Compose (docker-compose.dev.yml overrides most of these)
 
 # Database
-DATABASE_URL=postgresql://forte:forte@localhost:5432/forte
+DATABASE_URL=postgresql://forte:forte@postgres:5432/forte
 
 # Valkey (Redis-compatible)
-REDIS_URL=redis://localhost:6379
+REDIS_URL=redis://valkey:6379
+
+# JWT
+JWT_SECRET=change-me-in-production-use-a-long-random-string
 
 # API Server
 PORT=8000