🐛 fix(titlebar): 修复暗色主题标题栏图标白底

- 为默认品牌图标增加透明紧凑标题栏素材
- 增加独立标题栏资源解析并保留其他品牌图标现有展示
- 移除标题栏图标强制白色背景
- 补充默认图标、未知图标回退及透明素材测试

frontend/src/App.about-brand-lockup.test.ts

@@ -13,6 +13,9 @@ const brandIconsSource = readFileSync(
 const brandIconsDirectory = fileURLToPath(
   new globalThis.URL('../public/brand-icons/', import.meta.url),
 );
+const defaultTitlebarMark = fileURLToPath(
+  new globalThis.URL('../public/brand-marks/02-database-search-transparent.png', import.meta.url),
+);
 
 describe('about brand lockup', () => {
   it('uses a transparent lockup without a tile background on the about page', () => {
@@ -25,6 +28,15 @@ describe('about brand lockup', () => {
     expect(aboutLogoSnippet).toContain("boxShadow: 'none'");
   });
 
+  it('uses the transparent compact mark without a forced titlebar tile', () => {
+    expect(appSource).toContain('src={resolveBrandTitlebarSrc(brandIconId)}');
+
+    const titlebarLogoStart = appSource.indexOf('src={resolveBrandTitlebarSrc(brandIconId)}');
+    const titlebarLogoSnippet = appSource.slice(titlebarLogoStart, titlebarLogoStart + 640);
+    expect(titlebarLogoSnippet).toContain("background: 'transparent'");
+    expect(readFileSync(defaultTitlebarMark)).not.toHaveLength(0);
+  });
+
   it('keeps one shared lossless WebP asset for every selectable mascot', () => {
     const iconAssetPaths = brandIconsSource.match(/iconPath: '\/brand-icons\/\d{2}-.+\.webp'/g) || [];
     expect(iconAssetPaths).toHaveLength(10);

frontend/src/App.tsx

@@ -33,6 +33,7 @@ import {
   resolveBrandAboutSrc,
   resolveBrandDockSrc,
   resolveBrandIconSrc,
+  resolveBrandTitlebarSrc,
   type BrandIconId,
 } from './brand/brandIcons';
 import { composeMacOSDockIconBase64, shouldSyncMacOSDockIcon } from './brand/macDockIcon';
@@ -6908,7 +6909,7 @@ function App() {
           >
               <div style={{ display: 'flex', alignItems: 'center', gap: Math.max(6, Math.round(8 * effectiveUiScale)), fontWeight: 600, minWidth: 0 }}>
                   <img
-                    src={resolveBrandIconSrc(brandIconId)}
+                    src={resolveBrandTitlebarSrc(brandIconId)}
                     alt="GoNavi"
                     width={Math.max(24, Math.round(28 * effectiveUiScale))}
                     height={Math.max(24, Math.round(28 * effectiveUiScale))}
@@ -6919,7 +6920,7 @@ function App() {
                       objectFit: 'contain',
                       borderRadius: 8,
                       flexShrink: 0,
-                      background: '#fff',
+                      background: 'transparent',
                     }}
                   />
                   GoNavi

frontend/src/brand/brandIcons.test.ts

@@ -5,6 +5,7 @@ import {
   resolveBrandDockSrc,
   resolveBrandFullSrc,
   resolveBrandIconSrc,
+  resolveBrandTitlebarSrc,
 } from './brandIcons';
 
 describe('brand icon asset resolution', () => {
@@ -17,4 +18,12 @@ describe('brand icon asset resolution', () => {
       expect(resolveBrandDockSrc(icon.id)).toBe(selectedAsset);
     }
   });
+
+  it('uses the transparent compact mark for the default titlebar icon', () => {
+    const defaultTitlebarAsset = '/brand-marks/02-database-search-transparent.png';
+    expect(resolveBrandTitlebarSrc('02')).toBe(defaultTitlebarAsset);
+    expect(resolveBrandTitlebarSrc()).toBe(defaultTitlebarAsset);
+    expect(resolveBrandTitlebarSrc('unknown')).toBe(defaultTitlebarAsset);
+    expect(resolveBrandTitlebarSrc('01')).toBe(resolveBrandIconSrc('01'));
+  });
 });

frontend/src/brand/brandIcons.ts

@@ -16,6 +16,7 @@ export type BrandIconDefinition = {
   titleZh: string;
   titleEn: string;
   iconPath: string;
+  titlebarPath?: string;
 };
 
 export const DEFAULT_BRAND_ICON_ID: BrandIconId = '02';
@@ -34,6 +35,7 @@ export const BRAND_ICONS: BrandIconDefinition[] = [
     titleZh: '搜库小狗',
     titleEn: 'Database search',
     iconPath: '/brand-icons/02-database-search.webp',
+    titlebarPath: '/brand-marks/02-database-search-transparent.png',
   },
   {
     id: '03',
@@ -119,6 +121,11 @@ export function resolveBrandAboutSrc(id?: unknown): string {
   return resolveBrandIconSrc(id);
 }
 
+export function resolveBrandTitlebarSrc(id?: unknown): string {
+  const icon = resolveBrandIcon(id);
+  return icon.titlebarPath || icon.iconPath;
+}
+
 /** Dock uses the exact lossless WebP lockup rendered by BrandIconPicker. */
 export function resolveBrandDockSrc(id?: unknown): string {
   return resolveBrandIconSrc(id);