feat: enhance WelcomeDialog, export dialogs, GitStatusPanel, add CommandPalette, FindReplaceBar, and new converter dialogs

- WelcomeDialog: add quick start, feature showcase, keyboard shortcuts, recent files, version display
- ExportDocxDialog/ExportHtmlDialog/ExportPdfDialog: add header/footer, paper size, margin controls
- GitStatusPanel: full staging/unstaging, discard, commit workflow
- CommandPalette: fuzzy command search with keyboard navigation
- FindReplaceBar: find/replace with regex, case, whole-word options
- New dialogs: BatchMediaConverterDialog, HeaderFooterDialog, PdfEditorDialog, UniversalConverterDialog
- Tests: comprehensive coverage for all new/updated components

tests/component/modals/WordExportDialog.test.tsx

@@ -7,13 +7,11 @@ import { useEditorStore } from '@/stores/editor-store';
 import { useSettingsStore } from '@/stores/settings-store';
 
 vi.mock('@/lib/docx-export', () => ({
-  generateDocx: vi
-    .fn()
-    .mockResolvedValue(
-      new Blob([new Uint8Array([1, 2, 3])], {
-        type: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
-      })
-    ),
+  generateDocx: vi.fn().mockResolvedValue(
+    new Blob([new Uint8Array([1, 2, 3])], {
+      type: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+    })
+  ),
 }));
 
 vi.mock('@/lib/toast', () => ({