fix(canary-phase12): address audit findings before phase rollup

- Rename admin.Handler.Register → RegisterRoutes for parity with
  health.Handler.RegisterRoutes and token.Handler.RegisterAPIRoutes /
  RegisterManageRoutes / RegisterTriggerRoutes. Spec §6.3 line 558
  also illustrates the canonical wire-up as
  `adminH.RegisterRoutes(api)`.
- Drop the local strItoa helper in handler_test.go; use strconv.Itoa.
  The helper was a code-reviewer nit — equivalent stdlib already
  exists; fewer lines, less surface to drift.

Both findings are non-blocking but covered by the fix-in-phase rule
(no backlog rot). Phase 12 audits otherwise PASS on first dispatch:
- superpowers:code-reviewer: PASS
- general-purpose spec-adherence: PASS

PROJECTS/beginner/canary-token-generator/backend/cmd/canary/main.go

@@ -333,7 +333,7 @@ func mountAdminRoutes(
 	}
 	api.Route("/admin", func(adm chi.Router) {
 		adm.Use(middleware.OperatorBearer(cfg.Operator.Token))
-		adminH.Register(adm)
+		adminH.RegisterRoutes(adm)
 	})
 }
 

PROJECTS/beginner/canary-token-generator/backend/internal/admin/handler.go

@@ -79,7 +79,7 @@ func NewHandler(
 	}
 }
 
-func (h *Handler) Register(r chi.Router) {
+func (h *Handler) RegisterRoutes(r chi.Router) {
 	r.Get("/stats", h.GetStats)
 	r.Get("/tokens", h.ListTokens)
 	r.Post("/tokens/{"+urlParamID+"}/disable", h.DisableToken)

PROJECTS/beginner/canary-token-generator/backend/internal/admin/handler_test.go

@@ -11,6 +11,7 @@ import (
 	"log/slog"
 	"net/http"
 	"net/http/httptest"
+	"strconv"
 	"sync"
 	"testing"
 
@@ -158,7 +159,7 @@ func quietLogger() *slog.Logger {
 
 func newRouter(h *admin.Handler) chi.Router {
 	r := chi.NewRouter()
-	h.Register(r)
+	h.RegisterRoutes(r)
 	return r
 }
 
@@ -370,7 +371,7 @@ func TestAdmin_ListTokens_LimitCappedAt100(t *testing.T) {
 	repo := newFakeTokenRepo()
 	for i := range 150 {
 		repo.tokens = append(repo.tokens, seedToken(
-			"lim"+strItoa(i),
+			"lim"+strconv.Itoa(i),
 			token.TypeWebbug,
 			token.ChannelWebhook,
 		))
@@ -503,16 +504,3 @@ func TestAdmin_DisableToken_GetIsNotRouted(t *testing.T) {
 	))
 	require.Equal(t, http.StatusMethodNotAllowed, w.Code)
 }
-
-func strItoa(i int) string {
-	const digits = "0123456789"
-	if i == 0 {
-		return "0"
-	}
-	var out []byte
-	for i > 0 {
-		out = append([]byte{digits[i%10]}, out...)
-		i /= 10
-	}
-	return string(out)
-}

PROJECTS/beginner/canary-token-generator/backend/internal/admin/integration_test.go

@@ -62,7 +62,7 @@ func setupIntgStack(t *testing.T) *intgStack {
 	r.Route("/api", func(api chi.Router) {
 		api.Route("/admin", func(adm chi.Router) {
 			adm.Use(middleware.OperatorBearer(intgOperatorToken))
-			adminH.Register(adm)
+			adminH.RegisterRoutes(adm)
 		})
 	})