Develop (#55)

feat: optimize dashboard/search UX and simplify extension architecture

Redesign Dashboard with compact tool grid and recently used tools
Improve TopBar search UX with Cmd/Ctrl+K shortcut and better history navigation
Reorganize project structure into src/
Migrate i18n from react-i18next to chrome.i18n
Remove runtime language switch and settings page
Remove HTML/Markdown conversion tools
Clean up unused code, dead animations, redundant comments, and imports
Improve component consistency with shadcn/ui patterns
Replace hardcoded strings/colors with i18n tokens and theme tokens
Add comprehensive project documentation and coding standards
Fix CI artifact upload workflow and multiple TypeScript/test issues

Includes various refactors, UI polish, i18n cleanup, CI improvements,
and maintenance updates across the codebase.

src/utils/__tests__/clipboard.test.ts

@@ -0,0 +1,57 @@
+import { describe, expect, it, vi, beforeAll } from 'vitest';
+import { copyTextToClipboard, copyImageToClipboard } from '@/utils/clipboard';
+
+// Mock ClipboardItem for test environment
+class MockClipboardItem {
+  constructor(public items: Record<string, Blob>) {}
+}
+
+beforeAll(() => {
+  (globalThis as any).ClipboardItem = MockClipboardItem;
+});
+
+describe('clipboard', () => {
+  describe('copyTextToClipboard', () => {
+    it('复制成功时应返回 true', async () => {
+      const writeText = vi.fn().mockResolvedValue(undefined);
+      Object.assign(navigator, { clipboard: { writeText } });
+
+      const result = await copyTextToClipboard('test text');
+
+      expect(result).toBe(true);
+      expect(writeText).toHaveBeenCalledWith('test text');
+    });
+
+    it('复制失败时应返回 false', async () => {
+      const writeText = vi.fn().mockRejectedValue(new Error('Permission denied'));
+      Object.assign(navigator, { clipboard: { writeText } });
+
+      const result = await copyTextToClipboard('test text');
+
+      expect(result).toBe(false);
+    });
+  });
+
+  describe('copyImageToClipboard', () => {
+    it('复制成功时应返回 true', async () => {
+      const write = vi.fn().mockResolvedValue(undefined);
+      Object.assign(navigator, { clipboard: { write } });
+
+      const blob = new Blob(['png data'], { type: 'image/png' });
+      const result = await copyImageToClipboard(blob);
+
+      expect(result).toBe(true);
+      expect(write).toHaveBeenCalledTimes(1);
+    });
+
+    it('复制失败时应返回 false', async () => {
+      const write = vi.fn().mockRejectedValue(new Error('Permission denied'));
+      Object.assign(navigator, { clipboard: { write } });
+
+      const blob = new Blob(['png data'], { type: 'image/png' });
+      const result = await copyImageToClipboard(blob);
+
+      expect(result).toBe(false);
+    });
+  });
+});