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.

apps/desktop/README.md

@@ -35,8 +35,16 @@ pnpm --filter @parking/desktop bundle   # build the SPA + bundle the desktop app
 Requires the Rust toolchain and (on Linux) WebKitGTK 4.1 + libsoup-3 dev libraries. Under WSL2 the
 window needs a display (WSLg or an X server).
 
+## Auto-update
+
+Signed updates are built and published by `.gitea/workflows/release.yml` on a `vX.Y.Z` tag, mirrored
+to the public `mca/public_releases` repo (this repo is private; the updater runs on offline-first
+field appliances with no Gitea credentials, so its endpoint must be reachable unauthenticated —
+see that workflow's header and `wiki/decisions/desktop-shell-tauri.md`). The updater config and
+signing pubkey live in `tauri.conf.json`; the private signing key is held outside the repo, never
+committed.
+
 ## Not here (deliberately)
 
-Kiosk lockdown (fullscreen/no-decorations), auto-update, code signing, and launching Fastify from
-the shell are out of scope for the scaffold — on the appliance Fastify runs as its own service and
-this shell connects to it.
+Kiosk lockdown (fullscreen/no-decorations) and launching Fastify from the shell are out of scope for
+the scaffold — on the appliance Fastify runs as its own service and this shell connects to it.

apps/desktop/src-tauri/tauri.conf.json

@@ -41,9 +41,9 @@
   },
   "plugins": {
     "updater": {
-      "//": "Stable 'latest release' path on Gitea — redirects to the newest tag's latest.json (published by .gitea/workflows/release.yml). The updater GETs this, gets the manifest (platforms.linux-x86_64.{signature,url}), and compares versions. The release is reachable to the appliance only when it's brought online (phone hotspot); offline-first means a failed check is a no-op.",
+      "//": "Points at mca/public_releases, NOT this (private, source) repo — the updater runs on offline-first field appliances with no Gitea credentials, so the endpoint must be reachable unauthenticated. That repo is public and holds only compiled installers (no source), mirrored here by .gitea/workflows/release.yml. NOT the 'latest release' redirect: public_releases is shared across apps in the org, so 'latest' there could be someone else's release. This URL names our own most-recent tag directly (desktop-vX.Y.Z, bumped by the release workflow each publish) so a newer unrelated app release never shadows ours. The updater GETs this, gets the manifest (platforms.linux-x86_64.{signature,url}), and compares versions. The release is reachable to the appliance only when it's brought online (phone hotspot); offline-first means a failed check is a no-op.",
       "endpoints": [
-        "https://git.infra.msai.al/mca/parking_solution/releases/latest/download/latest.json"
+        "https://git.infra.msai.al/mca/public_releases/releases/download/desktop-latest/latest.json"
       ],
       "pubkey": "dW50cnVzdGVkIGNvbW1lbnQ6IG1pbmlzaWduIHB1YmxpYyBrZXk6IDgxNzg5RUQ1QkM0Q0FDRjYKUldUMnJFeTgxWjU0Z1RlNmhneDVZQlVVTVZZdGhJTkUxTGdDeGYwQSttZmNKVVp5WEdVMWlBb1YK"
     }