chore(electron): wire package.json scripts + main entry, gitignore build output

Follow-up to 218a584f - these edits (electron npm scripts, "main" field,
electron/electron-builder/electron-updater deps, dist-electron/**
gitignore) were made alongside that commit but got left unstaged when it
landed. No behavior change beyond what that commit already described.

package.json

@@ -1,6 +1,7 @@
 {
   "name": "bulwark-webmail",
   "version": "1.7.8",
+  "main": "dist-electron/main.js",
   "description": "Bulwark Webmail - a modern webmail client built for Stalwart Mail Server",
   "author": "Bulwark Webmail <bulwark@rbm.systems>",
   "license": "AGPL-3.0-only",
@@ -30,7 +31,11 @@
     "test:translations": "vitest run --no-isolate lib/__tests__/translations.test.ts",
     "test:integration": "bash integration/run-tests.sh",
     "prepare": "husky",
-    "typecheck": "tsc --noEmit"
+    "typecheck": "tsc --noEmit",
+    "build:standalone": "next build --webpack && node scripts/assemble-standalone.mjs",
+    "build:electron": "node scripts/build-electron.mjs",
+    "electron:dev": "npm run build:standalone && npm run build:electron && electron .",
+    "test:electron": "playwright test -c playwright.electron.config.ts"
   },
   "dependencies": {
     "@dnd-kit/core": "^6.3.1",
@@ -55,6 +60,7 @@
     "clsx": "^2.1.1",
     "date-fns": "^4.1.0",
     "dompurify": "^3.4.12",
+    "electron-updater": "^6.8.9",
     "jalaali-js": "^2.0.0",
     "jszip": "^3.10.1",
     "lucide-react": "^1.8.0",
@@ -88,6 +94,8 @@
     "@typescript-eslint/parser": "^8.59.0",
     "@vitejs/plugin-react": "^6.0.1",
     "@vitest/ui": "^4.1.5",
+    "electron": "^43.2.0",
+    "electron-builder": "^26.15.3",
     "esbuild": "^0.28.0",
     "eslint": "^9.39.4",
     "eslint-plugin-react": "^7.37.5",