desktop dev update channel: every push to main builds dev bundles (<next patch>-dev.<UTC>), the VDS signs and publishes dev/latest.json (newest 5); app channel setting stable|dev, background updater at start / 15 min / resume / channel switch, deferred while in use, no downgrade, autostart rewritten on every start, card shows version and channel

apps/desktop/src/card/Card.tsx

@@ -126,6 +126,7 @@ export function Card({ host, lang }: { host: CardHost; lang: CardLang }) {
           </Section>
         )}
       </div>
+      {s?.build && <footer className="tc-foot" data-testid="card-build">{T('build', { version: s.build.version, channel: T(s.build.channel === 'dev' ? 'chDev' : s.build.channel === 'beta' ? 'chBeta' : 'chStable') })}</footer>}
     </div>
   );
 }