feat(M7): electron-builder packaging (MSI + NSIS) + electron-updater

- electron-builder.yml: msi(fixed upgradeCode)+nsis x64, asarUnpack node-pty/ssh2, npmRebuild off, publish generic for latest.yml
- updater: packaged-only, OT_UPDATE_URL/OT_UPDATE_TOKEN env, ready+5s check, warn-only failures; auto-update channel is NSIS (MSI not supported by electron-updater)
- scripts dist/dist:dir; win-unpacked smoke verified (native modules load)

package.json

@@ -1,7 +1,7 @@
 {
   "name": "open-terminal",
   "productName": "OpenTerminal",
-  "version": "0.1.0",
+  "version": "0.7.0",
   "description": "Terminal with split panes, themes and fonts (XTerminal-inspired)",
   "main": "out/main/index.js",
   "author": "Bill",
@@ -10,7 +10,9 @@
     "dev": "electron-vite dev",
     "build": "electron-vite build",
     "preview": "electron-vite preview",
-    "typecheck": "tsc --noEmit -p tsconfig.node.json && tsc --noEmit -p tsconfig.web.json"
+    "typecheck": "tsc --noEmit -p tsconfig.node.json && tsc --noEmit -p tsconfig.web.json",
+    "dist": "electron-vite build && electron-builder --win msi nsis",
+    "dist:dir": "electron-vite build && electron-builder --win --dir"
   },
   "dependencies": {
     "@lydell/node-pty": "^1.2.0-beta.15",