[ui] route all native alert()/confirm() through the site notification system

Every browser alert()/confirm() now uses the app's UI instead of native dialogs
(no prompt() existed). Two new pieces:

- js/ui/confirmDialog.js — showConfirm(message, opts) -> Promise<boolean>, a styled
  `bv-modal modal-always-on-top` dialog (Confirm/Cancel/backdrop/Escape; danger variant
  focuses Cancel). Importable anywhere, so future confirmations use it too. It stacks
  above other modals and is typable thanks to the recent stacked-modal focus fix.
- js/ui/appNotify.js — notifyError/notifyStatus/notifySuccess routing to the app's
  NotificationController, for modules without a local showError; re-exports showConfirm.

Migrated: UploadModal (10 alert -> this.showError, 1 confirm), subscriptionHistory
(3 alert -> notify*, 1 confirm), MyVideosController (2), ProfileStorage/Wallet/Relay
controllers, profileModalController (2), settingsRestorePrompt (default confirm now
showConfirm), nostr/client deleteAllVersions. confirmSyncOverwrite helpers made async
(syncConflict already awaits confirmOverwrite).

Tests: tests/confirm-dialog.test.mjs (6 — confirm/cancel/backdrop/Escape resolution,
DOM cleanup, danger focus, no-DOM fallback). Build + lint clean; affected suites green.
(Note: build/lint don't parse JS — caught a multi-line-import split + a wrong import
path via module-import checks.)

Co-Authored-By: Claude Opus 4.8 <[email protected]>

js/ui/profileModal/ProfileRelayController.js

@@ -1,4 +1,5 @@
 import { devLogger, userLogger } from "../../utils/logger.js";
+import { showConfirm } from "../confirmDialog.js";
 import { sanitizeRelayList } from "../../nostr/nip46Client.js";
 
 const noop = () => {};
@@ -556,7 +557,7 @@ export class ProfileRelayController {
       reason: null,
     };
 
-    const confirmed = window.confirm("Restore the recommended relay defaults?");
+    const confirmed = await showConfirm("Restore the recommended relay defaults?", { confirmLabel: "Restore" });
     context.confirmed = confirmed;
     if (!confirmed) {
       context.reason = "cancelled";
@@ -604,9 +605,10 @@ export class ProfileRelayController {
       return;
     }
 
-    const confirmed = window.confirm(
-      `Remove ${url} from your relay list?`,
-    );
+    const confirmed = await showConfirm(`Remove ${url} from your relay list?`, {
+      confirmLabel: "Remove",
+      danger: true,
+    });
     if (!confirmed) {
       return;
     }