feat(admin): cloud injection and the 15-minute reconciler

Injection is a single UpdateOne of three licence fields, so it is
idempotent and safe to re-run. The control plane caches licence state for
60 seconds, so an injected licence takes effect within a minute with no
restart.

Deliver never fails its caller. The reconciler, not the issuance path, is
what actually guarantees a cloud instance ends up holding the licence admin
says it holds -- injection at issue time is best-effort and this is the
backstop.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

admin/cmd/main.go

@@ -13,6 +13,7 @@ import (
 	"github.com/joho/godotenv"
 	"github.com/mrhid6/vantage/admin/internal/config"
 	"github.com/mrhid6/vantage/admin/internal/db"
+	"github.com/mrhid6/vantage/admin/internal/inject"
 	"github.com/mrhid6/vantage/admin/internal/licensing"
 	"github.com/mrhid6/vantage/admin/internal/models"
 )
@@ -46,6 +47,10 @@ func main() {
 	}
 	idxCancel()
 
+	reconcileCtx, stopReconcile := context.WithCancel(context.Background())
+	defer stopReconcile()
+	inject.StartReconciler(reconcileCtx)
+
 	srv := &http.Server{
 		Addr:              cfg.Addr,
 		Handler:           http.NotFoundHandler(), // replaced in Task 8