fix(updater): compute the nightly version once and keep re-runs safe

Review follow-ups: the nightly version is resolved by a leading job and
handed to every build job, and the patch is bumped only when the base
tag already exists so the release-cut window stays below the imminent
release. A re-run never deletes a published nightly; only a draft left
by a failed run is replaced. Typed update-status literals in the
remaining specs carry the new channel fields.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

apps/web/src/app/app-update-notification-panel.component.spec.ts

@@ -14,6 +14,8 @@ const availableStatus: ElectronBridgeAppUpdateStatus = {
     manualDownloadUrl: 'https://github.com/4gray/iptvnator/releases/latest',
     status: ELECTRON_BRIDGE_APP_UPDATE_STATUSES.Available,
     supportedSelfUpdate: true,
+    channel: 'stable',
+    installedChannel: 'stable',
 };
 
 describe('AppUpdateNotificationPanelComponent', () => {

apps/web/src/app/services/app-update-install.service.spec.ts

@@ -12,6 +12,9 @@ const BASE_STATUS: ElectronBridgeAppUpdateStatus = {
     currentVersion: '0.23.0',
     status: ELECTRON_BRIDGE_APP_UPDATE_STATUSES.Idle,
     supportedSelfUpdate: true,
+    manualDownloadUrl: 'https://github.com/4gray/iptvnator/releases/latest',
+    channel: 'stable',
+    installedChannel: 'stable',
 };
 
 /**