feat(http): chi router skeleton + Google-style error response

internal/transport/http/router.go

@@ -0,0 +1,50 @@
+package httpx
+
+import (
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+)
+
+// RouterDeps bundles the dependencies needed to assemble the router.
+// MVP exposes only liveness/readiness probe hooks; later phases (auth
+// resolver, module handlers, etc.) will add fields here rather than
+// growing NewRouter's signature.
+type RouterDeps struct {
+	// HealthCheck is invoked from GET /healthz. Returning a non-nil
+	// error renders 503 with the error message as the body. If nil,
+	// /healthz unconditionally returns 200 "ok".
+	HealthCheck func(*http.Request) error
+	// ReadyCheck is invoked from GET /readyz with the same contract.
+	ReadyCheck func(*http.Request) error
+}
+
+// NewRouter builds the application's chi.Router with the standard
+// liveness/readiness endpoints attached. The return type is the
+// chi.Router interface (not *chi.Mux) so call sites depend only on
+// behaviour shared with future routing layers.
+func NewRouter(deps RouterDeps) chi.Router {
+	r := chi.NewRouter()
+
+	r.Get("/healthz", func(w http.ResponseWriter, req *http.Request) {
+		if deps.HealthCheck != nil {
+			if err := deps.HealthCheck(req); err != nil {
+				http.Error(w, err.Error(), http.StatusServiceUnavailable)
+				return
+			}
+		}
+		_, _ = w.Write([]byte("ok"))
+	})
+
+	r.Get("/readyz", func(w http.ResponseWriter, req *http.Request) {
+		if deps.ReadyCheck != nil {
+			if err := deps.ReadyCheck(req); err != nil {
+				http.Error(w, err.Error(), http.StatusServiceUnavailable)
+				return
+			}
+		}
+		_, _ = w.Write([]byte("ok"))
+	})
+
+	return r
+}