feat: phase 6 production hardening + DB-to-DB transfer

Security:
- Graceful shutdown: http.Server + signal.NotifyContext, 10s drain,
  retention sweeper cancelled before pool close
- Scoped API keys (migration 00006): ingest/read/write/admin enforced in
  auth middleware; scope picker + badges in Settings UI; scopeless legacy
  keys act as admin. Read-only keys now get 403 on ingest (verified live)
- nginx: baseline security headers on all responses, CSP scoped to SPA;
  fixed add_header inheritance shadowing
- better-auth rate limit enabled unconditionally (was gated on NODE_ENV,
  which the shipped .env sets to development)
- Mailpit moved to docker-compose.dev.yml; prod compose cannot expose it
- setup.sh generates PRIMORA_ENCRYPTION_KEY

Reliability/ops:
- Retention: per-project retention_{events,audit,webhook}_days
  (migration 00007, 0=off) + hourly RetentionSweeper; edit UI in Projects
- GET /api/v1/metrics Prometheus exposition
- compose: healthchecks + restart policies everywhere, dragonfly pinned
  to v2.0.0, depends_on service_healthy
- backup.sh/restore.sh (pg_dump -Fc + storage volume); restore verified
  against scratch postgres+volume
- .dockerignore: exclude target dirs (build context was 4.7GB)

Correctness/testing:
- DBX transfer endpoint: POST /db-connections/:id/transfer — SQL or Redis
  target, 1000-row bound, server-side creds (verified live pg→dragonfly)
- Pagination audit: ListComponents capped at 500 (auto-registers)
- CI: goose up/reset/up job + compose e2e-smoke job (smoke-e2e.sh
  verified locally: signup, bootstrap, scoped keys, ingest, metrics)
- k6 load sanity script: 6650 reqs, ~217/s, 0 real failures, p95 221ms
  (429s = configured rate limiter working)

Docs: DEPLOYMENT_GUIDE.md, PRODUCTION_READINESS.md; verify script
repaired (stale refs + set -e arithmetic abort). ROADMAP: phase 2 +
phase 6 marked complete.

Authored By: TDvorak <[email protected]>

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

infra/nginx/mailpit.conf

@@ -0,0 +1,12 @@
+# Dev-only: mounted into /etc/nginx/primora-extra/ by docker-compose.dev.yml.
+# Included inside the default server block — do not add a server{} here.
+location /mailpit/ {
+  set $upstream http://mailpit:8025;
+  rewrite ^/mailpit/?(.*)$ /$1 break;
+  proxy_pass $upstream;
+  proxy_http_version 1.1;
+  proxy_set_header Host $host;
+  proxy_set_header X-Real-IP $remote_addr;
+  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+  proxy_set_header X-Forwarded-Proto $scheme;
+}