fix(desktop): mirror signed releases to public repo for the updater

The updater endpoint pointed at mca/parking_solution's own Gitea "latest
release" redirect, but that repo is private and field appliances have no
Gitea credentials — every update check was silently failing. release.yml
now mirrors signed installers to mca/public_releases (public, installers
only) under a fixed desktop-latest tag; tauri.conf.json points there.
Rejected embedding a read token in the app instead, given the booth-operator
threat model.

Also: make the appliance-provisioning root_directory gotcha impossible to
skim past (boxed callout + explicit next-step pointers), after it caused a
second missed step on the park-2 install.

wiki/decisions/desktop-shell-tauri.md

@@ -2,7 +2,7 @@
 type: decision
 tags: [parking, decisions, desktop, frontend]
 sources: []
-updated: 2026-06-21
+updated: 2026-09-03
 status: settled
 ---
 
@@ -149,11 +149,7 @@ Per the user's choices — the operator **keeps OS access** (no fullscreen lockd
   offline), prompts the operator (i18n `update.prompt`), then `downloadAndInstall()` + `relaunch()`.
   Accepts that the appliance may be **offline** day-to-day and brought online (phone hotspot) only
   when an update is wanted — consistent with [[offline-first]] (no network dependency in *core*
-  operation; updates are out-of-band). Endpoint is the **self-hosted Gitea** "latest release"
-  path — `https://git.infra.msai.al/mca/parking_solution/releases/latest/download/latest.json`
-  — which redirects to the newest tag's `latest.json` (published by `.gitea/workflows/release.yml`).
-  The updater GETs it (200 + manifest, or 204 = up-to-date), reads `platforms.linux-x86_64.
-  {signature,url}`, and downloads the signed installer. **WS origin:** the desktop window's origin
+  operation; updates are out-of-band). **WS origin:** the desktop window's origin
   is `tauri://localhost` (Linux may also send `http://tauri.localhost`), so the backend's
   `WS_ALLOWED_ORIGINS` must include both or the live feed won't connect (documented in
   `apps/server/.env.example`).
@@ -165,8 +161,27 @@ Per the user's choices — the operator **keeps OS access** (no fullscreen lockd
   produced `.deb`/`.rpm`/`.AppImage` **plus their `.sig` updater signatures**; full `turbo run build
   lint` 14/14 green. *(This is the **updater** signing — distinct from OS-installer signing for
   Windows/macOS "unknown publisher", and from the [[atecc608]]/[[tpm]] **event** signing.)*
-- **Still deferred:** the actual update-hosting URL, OS-level installer signing
-  (Windows/macOS publisher trust), and the Windows kiosk-browser fallback path.
+- **Update-hosting endpoint (found broken, fixed 2026-09-03):** the endpoint originally pointed at
+  the **source repo's own** Gitea "latest release" redirect
+  (`.../mca/parking_solution/releases/latest/download/latest.json`) — but `mca/parking_solution` is
+  **private**, and the updater runs on offline-first field appliances with **no Gitea credentials**.
+  Every deployed update check was silently failing (swallowed by a `try/catch` in
+  `desktop-updater.ts`) — this was never field-verified, and it couldn't have worked as configured.
+  **Fix:** signed installers are now mirrored to a separate **public**, releases-only repo,
+  `mca/public_releases` (shared across apps in the org — see [[fleet-deployment-komodo]] sibling
+  infra), holding **only compiled installers, no source**. `tauri.conf.json`'s endpoint now points
+  there at a fixed `desktop-latest` tag (NOT that repo's generic "latest release" redirect, since
+  other apps publishing there would shadow ours — see the `desktop-latest` vs `desktop-<TAG>`
+  split below). `.gitea/workflows/release.yml` pushes to both repos: the private source repo (own
+  record) and the public mirror (what the updater and any human downloader actually use).
+  **Rejected alternative:** embedding a `read:repository` Gitea token in `tauri.conf.json`'s
+  updater `headers` so it could read the private repo directly — ruled out because that token would
+  ship inside every installed binary in the field, and this appliance's own threat model names the
+  **booth operator as the primary adversary** (see root `CLAUDE.md`); a leaked token scoped to the
+  whole private repo, with no cheap way to rotate it across appliances already in the field, was
+  judged worse than publishing installers-only.
+- **Still deferred:** OS-level installer signing (Windows/macOS publisher trust) and the Windows
+  kiosk-browser fallback path.
 
 ### Desktop in CI — two workflows, two purposes (added 2026-06-24)
 
@@ -174,7 +189,15 @@ The desktop bundle now runs in CI under **two distinct workflows** — keep the
 
 - **`.gitea/workflows/release.yml`** (tag `v*`) — the **signed, versioned release**: builds
   `.deb`/`.rpm`/`.AppImage` **+ their `.sig`** (updater key from secrets), assembles `latest.json`,
-  and publishes a Gitea Release. This is what the auto-updater consumes. Unchanged.
+  and publishes a Gitea Release **on `mca/parking_solution` (source, own record) AND mirrors it to
+  `mca/public_releases`** (public, installers-only — see the update-hosting-endpoint entry above for
+  why). The mirror step uses a second token, `RELEASES_MIRROR_TOKEN`
+  (`write:repository`, scoped for pushing into `public_releases` only — a CI-side secret, never
+  shipped to any client, distinct from the embedded updater *pubkey*). It publishes two tags there:
+  `desktop-<TAG>` (versioned, permanent, for audit/rollback) and `desktop-latest` (moving — existing
+  assets deleted then re-uploaded each release, since Gitea has no per-app "latest" concept and this
+  repo is shared across apps). `latest.json`'s asset URL and `tauri.conf.json`'s updater endpoint
+  both point at `desktop-latest`. This is what the auto-updater actually consumes.
 - **`.gitea/workflows/build-desktop.yml`** (push to `dev`/`main`) — a **per-commit test build**:
   compiles `.deb` + `.AppImage` only (`pnpm --filter @parking/desktop bundle --bundles deb,appimage`)
   and publishes them to a **rolling per-branch pre-release** (tag `desktop-<branch>`). **Unsigned** —