Coil desktop builds carry upstream's permanently-dead 'Check for updates' control

[radroid]

Found during the 2026-08-14 sync seam review. SidebarUpdatePill gates only on isElectron, but Coil builds ship no upstream update feed (T3CODE_DESKTOP_UPDATE_REPOSITORY: disabled → no app-update.yml → hasUpdateFeedConfig false → canCheckForUpdate always false). Every Coil desktop build shows a permanently disabled 'Check for updates' button in the sidebar footer — a slot upstream pingdotgg#6210 just made scarcer — right next to the fork's real update mechanism (CoilUpdateToast). Same dead control in SettingsPanels.tsx. Upstream keeps investing in it (pingdotgg#6504 added an animated status icon this cycle).

Decide: gate the pill/settings section on state?.enabled (a new seam row), or record the dead control on the seam ledger as accepted. Two related fork-polish gaps from the same review, fine to fold in here or split:

• The fork's notifyOnNeedsInput setting registers nothing in settingsSearch.ts — unfindable via settings search, no scroll anchor.
• PWA naming missed the Rename the fork's identity from t3x to coil (everything except the landing site) #71 rename: apps/web/index.html apple-mobile-web-app-title and apps/web/public/manifest.webmanifest name/short_name/description still say 'T3 Code' (these are the install-time labels for the fork's own PWA/Web Push feature); manifest colors also predate the OKLCH theme work.