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>

apps/backend/internal/handlers/http.go

@@ -29,6 +29,7 @@ func (h *HTTPHandler) Register(router *gin.Engine) {
 	router.GET("/api/v1/health/liveness", h.liveness)
 	router.GET("/api/v1/health/readiness", h.readiness)
 	router.GET("/api/v1/openapi.yaml", h.openapi)
+	router.GET("/api/v1/metrics", h.metrics)
 
 	api := router.Group("/api/v1")
 	api.GET("/me", h.me)
@@ -91,6 +92,7 @@ func (h *HTTPHandler) Register(router *gin.Engine) {
 	api.GET("/projects/:projectID/db-connections/:connectionID/foreign-keys", h.dbxForeignKeys)
 	api.POST("/projects/:projectID/db-connections/:connectionID/query", h.dbxQuery)
 	api.POST("/projects/:projectID/db-connections/:connectionID/redis", h.dbxRedis)
+	api.POST("/projects/:projectID/db-connections/:connectionID/transfer", h.dbxTransfer)
 	api.GET("/projects/:projectID/integrations", h.listIntegrations)
 	api.POST("/projects/:projectID/integrations", h.createIntegration)
 	api.DELETE("/projects/:projectID/integrations/:integrationID", h.deleteIntegration)
@@ -123,6 +125,12 @@ func (h *HTTPHandler) openapi(c *gin.Context) {
 	c.File("openapi/openapi.yaml")
 }
 
+// metrics is intentionally unauthenticated — Prometheus scrapes it. Restrict
+// it at the edge if the deployment is public-facing.
+func (h *HTTPHandler) metrics(c *gin.Context) {
+	c.Data(http.StatusOK, "text/plain; version=0.0.4; charset=utf-8", []byte(h.Metrics.RenderPrometheus()))
+}
+
 func (h *HTTPHandler) me(c *gin.Context) {
 	actor, ok := middleware.RequireActor(c)
 	if !ok {