feat(desktop): wire updater endpoint to self-hosted Gitea + document Tauri WS origin

Point the Tauri updater at the real self-hosted Gitea "latest release" path:
https://git.infra.msai.al/mca/parking_solution/releases/latest/download/latest.json
— redirects to the newest tag's latest.json published by release.yml. Verified
against tauri-plugin-updater: it GETs the endpoint (200 + manifest / 204 = up to
date) and reads platforms.linux-x86_64.{signature,url}.

Document the desktop WS origin: the Tauri window loads from tauri://localhost
(Linux may also send http://tauri.localhost), which is NOT same-origin with the
backend, so WS_ALLOWED_ORIGINS must include both or the live feed won't connect.
Added both to apps/server/.env.example.

Updated the as-built in wiki/decisions/desktop-shell-tauri.md. Also carries an
unrelated plans.namePlaceholder copy tweak already in the tree. turbo build lint
14/14 green.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

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

@@ -41,8 +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.",
       "endpoints": [
-        "https://UPDATES.EXAMPLE.invalid/parking/{{target}}/{{arch}}/{{current_version}}"
+        "https://git.infra.msai.al/mca/parking_solution/releases/latest/download/latest.json"
       ],
       "pubkey": "dW50cnVzdGVkIGNvbW1lbnQ6IG1pbmlzaWduIHB1YmxpYyBrZXk6IDgxNzg5RUQ1QkM0Q0FDRjYKUldUMnJFeTgxWjU0Z1RlNmhneDVZQlVVTVZZdGhJTkUxTGdDeGYwQSttZmNKVVp5WEdVMWlBb1YK"
     }