An Electron client for the desktop store

The desktop store put the catalog on ordinary computers, and then asked people to
open a terminal — which on Windows is not even a workable ask, because the
installer is `curl … | sh`. This is the window: a grid of cards, one click to
install a title into the application menu, one to play it, one to remove it.

The CLI stays the product. Every action runs `desktop_store.py --json`, so there
is one catalog logic, one state file and one delete guard; the window never
touches the filesystem itself. That is also why the engine grew `--json` first
rather than this app growing a parser for prose.

It doubles as the Windows install path: with no store on the machine, the app
downloads the engine, the shared core and a config into the same folder the shell
installer would use — Node's https, no curl. An engine older than 1.1.0 cannot be
driven from a window, so the client checks the version and offers to refresh it
instead of failing on the first call.

Deliberate choices worth knowing:

- No renderer framework and no build step. Plain HTML, CSS and JS, one runtime
  dependency. The whole UI is readable in one sitting.
- `contextIsolation` on, `nodeIntegration` off, `sandbox` on, a CSP that permits
  only the app's own script and stylesheet plus images over HTTPS. The renderer
  can do exactly what preload.js exposes and nothing else.
- English and Hungarian, following the system language. The CLIs and the docs stay
  English; this is the one end-user surface where that is not enough.
- `ENGINES` is a list with one entry. The RetroArch store has the same command
  shape, so adding it is an entry, not a rewrite.

Two ways to test it without a working installation in the way: `npm run smoke`
drives the bridge with no window at all, and `npm run uitest` loads the window
once and reports what rendered — the only way a renderer error would otherwise be
noticed, since the main process log stays empty. Both accept a sandbox store
through STORE_ROOT / SMOKE_HOME.

Verified on macOS arm64, including the packaged .app: the store is found, ten
titles list, a sync installs three, and the window renders them as installed with
their Play and Remove buttons. Linux and Windows are unproven, as they are for the
CLI itself.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

package.json

@@ -0,0 +1,59 @@
+{
+  "name": "warp-engine-desktop-gui",
+  "productName": "WarpEngine Store",
+  "version": "1.0.0",
+  "description": "Graphical client for a WarpEngine desktop store: install the catalog into your own application menu.",
+  "license": "MIT",
+  "author": "Teletype Games <games@teletype.hu>",
+  "homepage": "https://git.teletypegames.org/stores/warp-engine-desktop-gui",
+  "main": "main.js",
+  "engines": {
+    "node": ">=22"
+  },
+  "scripts": {
+    "start": "electron .",
+    "smoke": "node scripts/smoke.js",
+    "dist": "electron-builder",
+    "dist:mac": "electron-builder --mac",
+    "dist:win": "electron-builder --win",
+    "dist:linux": "electron-builder --linux",
+    "uitest": "electron . --selftest"
+  },
+  "devDependencies": {
+    "electron": "^43.4.0",
+    "electron-builder": "^26.15.3"
+  },
+  "build": {
+    "appId": "org.teletypegames.warpstore.gui",
+    "productName": "WarpEngine Store",
+    "files": [
+      "main.js",
+      "preload.js",
+      "lib/**/*",
+      "renderer/**/*"
+    ],
+    "mac": {
+      "category": "public.app-category.games",
+      "target": [
+        "dmg",
+        "zip"
+      ]
+    },
+    "win": {
+      "target": [
+        "nsis",
+        "portable"
+      ]
+    },
+    "linux": {
+      "category": "Game",
+      "target": [
+        "AppImage",
+        "deb"
+      ]
+    }
+  },
+  "allowScripts": {
+    "electron@43.4.0": true
+  }
+}