fix: stabilize renderer state and lifecycle updates

Prevent stale history, account, diagnostics, and language updates from repainting newer state. Keep queue virtualization, panel sizing, telemetry, cancellation, and runtime timing consistent across rapid UI changes. Strengthen painted-frame and lifecycle regression coverage, and brand packaged Windows metadata with the product publisher.

tests/startup-renderer.test.js

@@ -3,7 +3,7 @@ const assert = require('node:assert/strict');
 const { EventEmitter } = require('node:events');
 const fs = require('node:fs');
 const path = require('node:path');
-const { configureStartupRenderer, createStartupWindow } = require('../lib/startup-renderer');
+const { configureStartupRenderer, createStartupWindow, resolveStartupLanguage } = require('../lib/startup-renderer');
 
 class TestBrowserWindow extends EventEmitter {
   constructor(options) {
@@ -12,6 +12,7 @@ class TestBrowserWindow extends EventEmitter {
     this.showCalls = 0;
     this.startupEvents = [];
     this.loadError = new Error('renderer load failed');
+    this.loadOptions = null;
   }
 
   once(eventName, listener) {
@@ -23,8 +24,9 @@ class TestBrowserWindow extends EventEmitter {
     this.showCalls++;
   }
 
-  loadFile(target) {
+  loadFile(target, options) {
     this.startupEvents.push(`load:${target}`);
+    this.loadOptions = options;
     return Promise.reject(this.loadError);
   }
 }
@@ -41,6 +43,13 @@ test('configureStartupRenderer disables hardware acceleration for a Windows Remo
   assert.equal(calls, 1);
 });
 
+test('resolveStartupLanguage accepts only the supported persisted language', () => {
+  assert.equal(resolveStartupLanguage({ globalSettings: { language: 'de' } }), 'de');
+  assert.equal(resolveStartupLanguage({ globalSettings: { language: 'en' } }), 'en');
+  assert.equal(resolveStartupLanguage({ globalSettings: { language: 'fr' } }), 'en');
+  assert.equal(resolveStartupLanguage(null), 'en');
+});
+
 test('createStartupWindow forces the main window to start hidden', () => {
   const startup = createStartupWindow(TestBrowserWindow, { width: 1100, show: true });
 
@@ -85,3 +94,12 @@ test('startup load forwards a rejected navigation to the error handler', async (
 
   assert.equal(handledError, startup.window.loadError);
 });
+
+test('startup load forwards navigation options before the renderer becomes visible', async () => {
+  const startup = createStartupWindow(TestBrowserWindow, {});
+  const options = { query: { language: 'de' } };
+
+  await startup.load('renderer/index.html', () => {}, options);
+
+  assert.deepEqual(startup.window.loadOptions, options);
+});