feat(updater): nightly builds and a stable/nightly update channel (#1608)

* feat(updater): nightly builds and a stable/nightly update channel

Every master push publishes its artifacts as a prerelease of
4gray/iptvnator-nightly instead of the rolling test-master draft, with a
version of <next patch>-nightly.<commit date>.<run number> applied in
every build job. Settings → About gains an Update channel switch;
AppUpdateService re-points electron-updater per check (feed repository,
allowPrerelease, channel name, allowDowngrade reset) and reads release
notes from the repository the requested version belongs to. Channel
switches are forward-only: a nightly build stays until a newer stable
release exists.

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

* 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>

* test(packaging): expect the nightly-version prerequisite in the build workflow graph

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

---------

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

libs/shared/interfaces/src/lib/electron-api.interface.ts

@@ -1,3 +1,4 @@
+import type { AppUpdateChannel } from './app-update-channel.util';
 import type { SourceProbeContext, SourceHealthResult } from './source-health';
 import type { XtreamConnectionFailure } from './xtream-connection-test';
 import type {
@@ -263,7 +264,12 @@ export interface ElectronBridgeAppUpdateStatus {
     progress?: ElectronBridgeAppUpdateProgress;
     error?: string;
     supportedSelfUpdate: boolean;
+    /** Release page for the configured channel; opened for manual installs. */
     manualDownloadUrl: string;
+    /** Channel the updater checks (`Settings.updateChannel`, mirrored). */
+    channel: AppUpdateChannel;
+    /** Channel the running build came from, read off its version string. */
+    installedChannel: AppUpdateChannel;
 }
 
 export type ElectronBridgeAppUpdateReleaseNotesDirection = 'previous' | 'next';