Bump turbo-rails for Turbo.offline.clearCache()

Simplify the clear-offline-cache controller to use the new
Turbo.offline.clearCache() API instead of messaging the service
worker directly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/javascript/controllers/clear_offline_cache_controller.js

@@ -1,8 +1,8 @@
 import { Controller } from "@hotwired/stimulus"
+import { Turbo } from "@hotwired/turbo-rails"
 
 export default class extends Controller {
-  async clearCache() {
-    const registration = await navigator.serviceWorker?.ready
-    registration?.active?.postMessage({ action: "clearCache" })
+  clearCache() {
+    Turbo.offline.clearCache()
   }
 }