chore(electron): align engines.node with root package.json (drop Node 20.x)

The root package.json was updated in 52f3285d to drop Node 20.x support
(http-proxy-middleware 4.x requirement). electron/package.json had no
engines field declared, leaving the desktop build implicitly permissive.

Adds the same constraint (>=22.22.2 <23 || >=24.0.0 <27) to keep the
electron workspace consistent with the root engine policy.

Refs: #2228

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

electron/package.json

@@ -9,6 +9,9 @@
   },
   "license": "MIT",
   "homepage": "https://omniroute.online",
+  "engines": {
+    "node": ">=22.22.2 <23 || >=24.0.0 <27"
+  },
   "scripts": {
     "start": "electron .",
     "dev": "electron . --no-sandbox",