Fix storage credentials persistence on profile switch

This change ensures that cloud storage credentials are not leaked between Nostr profiles when switching accounts in the UI.

Changes:
- Imported `storageService` in `js/app.js` to enable the `bitvid:auth-changed` event listener to correctly lock the previous profile's storage session.
- Updated `ProfileModalController.populateStoragePane` to explicitly clear the storage form before loading new data.
- Enhanced `ProfileModalController.handleClearStorage` to fully reset the form state, including the provider selection and visibility toggles.

Verified with a reproduction script (`reproduce_storage_isolation.mjs`) that `StorageService` correctly isolates data by pubkey at the backend level. The UI fixes address the frontend persistence issue.

js/app.js

@@ -53,6 +53,7 @@ import {
 } from "./feedEngine/index.js";
 import watchHistoryService from "./watchHistoryService.js";
 import r2Service from "./services/r2Service.js";
+import storageService from "./services/storageService.js";
 import {
   getVideoNoteErrorMessage,
   normalizeVideoNotePayload,

js/ui/profileModalController.js

@@ -8974,6 +8974,8 @@ export class ProfileModalController {
     const storageService = this.services.storageService;
     const pubkey = this.normalizeHexPubkey(this.getActivePubkey());
 
+    this.handleClearStorage();
+
     if (!pubkey) {
       // Not logged in
       if (this.storageUnlockSection) this.storageUnlockSection.classList.add("hidden");
@@ -9300,6 +9302,8 @@ export class ProfileModalController {
     this.storageBucketInput.value = "";
     this.storagePrefixInput.value = "";
     this.storageDefaultInput.checked = false;
+    this.storageProviderInput.value = "cloudflare_r2";
+    this.updateStorageFormVisibility();
     this.setStorageFormStatus("", "info");
   }