feat(updater): fixed-URL auto-update channel + silent retries

The auto-update system used a per-version publish URL
(releases/download/v${version}), so each installed build only ever
checked its own release page for new versions. To deliver an update we
had to manually copy the new manifest into every old release — easy to
forget, and any half-uploaded state showed users red "check failed"
banners.

Architectural fix:

- New rolling 'update-channel' Gitea release. publish.url is now a
  fixed path (.../releases/download/update-channel) that never moves.
- release.ps1 uploads each new build to three places:
    1. vX.Y.Z          (historical archive + changelog)
    2. update-channel  (what every client polls)
    3. -BridgeTags     (transition: also fill in old releases so users
                       still on those versions can find the new build)
- upload-release-assets.ps1 gains -AssetVersion to upload version-X.Y.Z
  artifacts into a non-version tag (channel/bridge).

Resilience fixes for the updater itself:

- Hourly checks and the boot check now run in SILENT mode: network
  errors don't promote to a red error state, they're logged and
  retried on the next tick. Only user-initiated "Check now" surfaces
  errors. This prevents the cascade of "Ошибка проверки" cards on
  flaky networks or partial uploads.
- Boot check retries up to 3 times (30s/2m/5m backoff) before giving
  up until the hourly tick.
- Track lastCheckedAt; "Up to date" subtitle now shows "checked Nm ago".

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

package.json

@@ -88,7 +88,7 @@
     },
     "publish": {
       "provider": "generic",
-      "url": "https://xn--90adajar8af4h.xn--p1ai/git/AnRil/laude/releases/download/v${version}",
+      "url": "https://xn--90adajar8af4h.xn--p1ai/git/AnRil/laude/releases/download/update-channel",
       "channel": "latest"
     }
   }