security: P1/P2 hardening — rate limiting, CORS, Redis auth, network isolation

- Add Redis-based sliding window rate limiting on login, register, forgot-password, reset-password
- Fix user enumeration: register returns generic 200 for both new and existing emails
- Add Redis authentication (requirepass) and password in .env
- Docker network isolation: postgres/redis on internal-only network
- Whitelist Stripe redirect origins (prevent open redirect)
- Add 10MB request size limit on trace ingestion
- Limit API keys to 10 per user
- Add CORS headers via middleware (whitelist agentlens.vectry.tech + localhost)
- Reduce JWT max age from 30 days to 7 days

.env.example

@@ -12,5 +12,8 @@ POSTGRES_USER=agentlens
 POSTGRES_PASSWORD=
 POSTGRES_DB=agentlens
 
+# Redis
+REDIS_PASSWORD=          # Generate with: openssl rand -base64 24
+
 # Email (optional — email features disabled if not set)
 EMAIL_PASSWORD=