perf(electron): load the main-process startup wiring after the window starts loading (#1702)

Registering IPC handlers costs 0.4 ms; evaluating the modules behind them (axios, drizzle-orm, better-sqlite3, electron-updater, fix-path) before the window could load was the real cost. main.ts now keeps only the pre-paint wiring and loads the rest as the deferred-events.js chunk inside the main window's did-start-loading listener, where the import and its registrations complete before any renderer invoke can arrive.

Interleaved A/B on the performance build: app.whenReady 323 -> 265 ms, did-finish-load 499 -> 447 ms; J1 journey spawnToDidFinishLoad ~405 -> ~365 ms with identical counters. Packaging ships the chunk explicitly, verify:package-layout requires it, and the benchmark build identity hashes it.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tools/packaging/verify-electron-package-layout.mjs

@@ -474,13 +474,15 @@ function verifyPackagedPackageMetadata(resourceDir, errors) {
 
 /**
  * The main-process entry is split: `main.js` enables the V8 compile cache and
- * requires `main.app.js`, the application bundle. nx-electron packages the
+ * requires `main.app.js`, the application bundle, which loads the
+ * `deferred-events.js` chunk once the window starts loading. nx-electron packages the
  * backend through an allowlist, so a missing bundle only surfaces as an
  * uncaught "Cannot find module" at launch; fail the layout check instead.
  */
 const REQUIRED_MAIN_PROCESS_ENTRIES = [
     '/electron-backend/main.js',
     '/electron-backend/main.app.js',
+    '/electron-backend/deferred-events.js',
     '/electron-backend/main.preload.js',
 ];