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>

.changes/electron-deferred-startup-wiring.md

@@ -0,0 +1,8 @@
+---
+type: perf
+area: electron
+---
+
+The desktop app now opens its window before it prepares the portal, program
+guide, download, player and update machinery, and does that preparation while
+the window is already loading, so the first screen appears sooner.