feat(api): M4.2 — REST surface + pgx Postgres store + OpenAPI 3.1

Full M4.2 deliverable: 16 endpoints (tenants CRUD + lifecycle, catalog, entitlements, API keys with argon2 hashing, audit append + filter), Store interface with pgx-backed Postgres + in-memory parallel implementations exercised by the same eachStore harness, openapi.yaml at 3.1 with kin-openapi contract test. M4.3 adds auth.

Refs: M4.2

internal/server/catalog.go

@@ -0,0 +1,145 @@
+package server
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"gitea.meghsakha.com/platform/tenant-registry/internal/store"
+)
+
+// catalog is hard-coded for now. PRODUCT_INTEGRATION_SPEC.md §10 has products
+// publish a manifest to `cdn.breakpilot.com`; this list will be sourced
+// from those manifests once M6.3 / M7.2 wire it up.
+var catalog = []store.CatalogEntry{
+	{
+		Key: "certifai", Name: "CERTifAI",
+		Description:   "Self-hosted GDPR-compliant AI dashboard.",
+		PlansRequired: []string{"professional", "enterprise"},
+		SupportsTrial: true,
+	},
+	{
+		Key: "compliance", Name: "Compliance",
+		Description:   "DSFA / TOM / VVT generation; evidence capture.",
+		PlansRequired: []string{"starter", "professional", "enterprise"},
+		SupportsTrial: true,
+	},
+}
+
+func (s *Server) getCatalog(w http.ResponseWriter, _ *http.Request) {
+	writeJSON(w, http.StatusOK, map[string]any{"items": catalog})
+}
+
+type catalogRequestReq struct {
+	TenantID string `json:"tenant_id"`
+	Product  string `json:"product"`
+}
+
+// catalogRequest — customer requests a non-subscribed product. Today this
+// just emits an audit event tagged so the eventual ERPNext-Lead step
+// (M11.1) can pick it up.
+func (s *Server) catalogRequest(w http.ResponseWriter, r *http.Request) {
+	var in catalogRequestReq
+	if !decodeJSON(w, r, &in) {
+		return
+	}
+	if in.TenantID == "" || in.Product == "" {
+		writeError(w, http.StatusBadRequest, "invalid_input", "tenant_id and product are required")
+		return
+	}
+	if !isKnownProduct(in.Product) {
+		writeError(w, http.StatusBadRequest, "unknown_product", "product is not in the catalog")
+		return
+	}
+
+	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
+	defer cancel()
+
+	if _, err := s.Store.GetTenant(ctx, in.TenantID); err != nil {
+		if mapStoreError(w, err) {
+			return
+		}
+		writeError(w, http.StatusInternalServerError, "internal", err.Error())
+		return
+	}
+
+	s.emitAudit(ctx, r, store.AuditEvent{
+		TenantID: in.TenantID, Action: "catalog.requested",
+		TargetID: in.Product, TargetType: "product",
+		Metadata: map[string]interface{}{"product": in.Product},
+	})
+
+	writeJSON(w, http.StatusAccepted, map[string]string{
+		"status":  "accepted",
+		"message": "request recorded; sales will be in touch",
+	})
+}
+
+// catalogTrialRequest — customer self-serves a 14-day trial of a product
+// that supports trial. Provisions the entitlement immediately so the
+// product can be used right away.
+func (s *Server) catalogTrialRequest(w http.ResponseWriter, r *http.Request) {
+	var in catalogRequestReq
+	if !decodeJSON(w, r, &in) {
+		return
+	}
+	if in.TenantID == "" || in.Product == "" {
+		writeError(w, http.StatusBadRequest, "invalid_input", "tenant_id and product are required")
+		return
+	}
+	entry, ok := lookupCatalogEntry(in.Product)
+	if !ok {
+		writeError(w, http.StatusBadRequest, "unknown_product", "product is not in the catalog")
+		return
+	}
+	if !entry.SupportsTrial {
+		writeError(w, http.StatusBadRequest, "trial_unavailable", "product does not support self-serve trial")
+		return
+	}
+
+	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
+	defer cancel()
+
+	if _, err := s.Store.GetTenant(ctx, in.TenantID); err != nil {
+		if mapStoreError(w, err) {
+			return
+		}
+		writeError(w, http.StatusInternalServerError, "internal", err.Error())
+		return
+	}
+
+	expiresAt := time.Now().UTC().Add(14 * 24 * time.Hour)
+	tp, err := s.Store.UpsertTenantProduct(ctx, store.TenantProduct{
+		TenantID: in.TenantID, Product: in.Product, Enabled: true,
+		Config: map[string]interface{}{"source": "trial"}, ExpiresAt: &expiresAt,
+	})
+	if err != nil {
+		if mapStoreError(w, err) {
+			return
+		}
+		writeError(w, http.StatusInternalServerError, "internal", err.Error())
+		return
+	}
+
+	s.emitAudit(ctx, r, store.AuditEvent{
+		TenantID: in.TenantID, Action: "catalog.trial_started",
+		TargetID: in.Product, TargetType: "product",
+		Metadata: map[string]interface{}{"product": in.Product, "expires_at": expiresAt.Format(time.RFC3339)},
+	})
+
+	writeJSON(w, http.StatusCreated, tp)
+}
+
+func isKnownProduct(key string) bool {
+	_, ok := lookupCatalogEntry(key)
+	return ok
+}
+
+func lookupCatalogEntry(key string) (store.CatalogEntry, bool) {
+	for _, e := range catalog {
+		if e.Key == key {
+			return e, true
+		}
+	}
+	return store.CatalogEntry{}, false
+}