refactor: reorganize directory structure into src/

Move all source code directories into src/ for cleaner project structure:
- pages/, components/, utils/, config/, providers/, types/, lib/, assets/, entrypoints/ → src/
- Use WXT srcDir config to resolve @/ alias to src/
- Update tsconfig, vitest, eslint, tailwind configs
- Remove scattered README.md files from subdirectories
- Update documentation (AGENTS.md, CODING_STANDARDS.md, README.md)
- Fix pre-existing lint error in RouterProvider.tsx

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/entrypoints/__tests__/background.test.ts

@@ -0,0 +1,144 @@
+import { describe, expect, it, vi, beforeEach } from 'vitest';
+import {
+  createAllContextMenus,
+  parseContextMenuClick,
+  CONTEXT_MENU_CONFIGS,
+  MAX_PAYLOAD_LENGTH,
+} from '@/utils/contextMenu';
+import { MessageAction } from '@/utils/messages';
+
+describe('background 菜单注册与分流', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  describe('菜单注册', () => {
+    it('应该调用 createAllContextMenus 创建所有菜单项', () => {
+      createAllContextMenus();
+
+      expect(chrome.contextMenus.create).toHaveBeenCalledTimes(CONTEXT_MENU_CONFIGS.length);
+    });
+
+    it('应该创建父级菜单 Testing Tools', () => {
+      createAllContextMenus();
+
+      expect(chrome.contextMenus.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          id: 'testing-tools-parent',
+          title: 'Testing Tools',
+        }),
+      );
+    });
+
+    it('应该创建 JWT 解析子菜单', () => {
+      createAllContextMenus();
+
+      expect(chrome.contextMenus.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          id: 'jwt',
+          title: '🔑 解析 JWT',
+          parentId: 'testing-tools-parent',
+        }),
+      );
+    });
+
+    it('应该创建网页链接转二维码子菜单', () => {
+      createAllContextMenus();
+
+      expect(chrome.contextMenus.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          id: 'qrCode-page',
+          title: '🔗 网页链接转二维码',
+          contexts: ['page'],
+        }),
+      );
+    });
+  });
+
+  describe('菜单点击解析', () => {
+    const createMockOnClickData = (
+      overrides: Partial<chrome.contextMenus.OnClickData> = {},
+    ): chrome.contextMenus.OnClickData => ({
+      menuItemId: 'test',
+      editable: false,
+      pageUrl: 'https://example.com',
+      ...overrides,
+    });
+
+    it('当有 selectionText 时应返回对应的 featureKey 和 payload', () => {
+      const info = createMockOnClickData({
+        menuItemId: 'jwt',
+        selectionText: 'test-token',
+      });
+
+      const result = parseContextMenuClick('jwt', info);
+
+      expect(result).toEqual({
+        success: true,
+        data: { featureKey: 'jwt', payload: 'test-token' },
+      });
+    });
+
+    it('当没有 selectionText 和 srcUrl 时应返回错误', () => {
+      const info = createMockOnClickData({
+        menuItemId: 'unknown',
+        pageUrl: undefined,
+      });
+
+      const result = parseContextMenuClick('unknown', info);
+
+      expect(result).toEqual({
+        success: false,
+        error: '无法获取有效数据',
+      });
+    });
+
+    it('当文本超过最大长度限制时应截断', () => {
+      const longText = 'a'.repeat(MAX_PAYLOAD_LENGTH + 1000);
+      const info = createMockOnClickData({
+        menuItemId: 'textStatistics',
+        selectionText: longText,
+      });
+
+      const result = parseContextMenuClick('textStatistics', info);
+
+      expect(result.success).toBe(true);
+      expect(result.data?.payload.length).toBe(MAX_PAYLOAD_LENGTH);
+    });
+
+    it('当文本未超过最大长度限制时应保持原样', () => {
+      const shortText = 'short text';
+      const info = createMockOnClickData({
+        menuItemId: 'textStatistics',
+        selectionText: shortText,
+      });
+
+      const result = parseContextMenuClick('textStatistics', info);
+
+      expect(result).toEqual({
+        success: true,
+        data: { featureKey: 'textStatistics', payload: 'short text' },
+      });
+    });
+
+    it('应该正确处理页面 URL 菜单点击', () => {
+      const info = createMockOnClickData({
+        menuItemId: 'storageCleaner',
+        pageUrl: 'https://example.com/page',
+      });
+
+      const result = parseContextMenuClick('storageCleaner', info);
+
+      expect(result).toEqual({
+        success: true,
+        data: { featureKey: 'storageCleaner', payload: 'https://example.com/page' },
+      });
+    });
+  });
+
+  describe('消息类型定义', () => {
+    it('CONTEXT_MENU_CLICKED 消息类型应正确定义', () => {
+      expect(MessageAction.CONTEXT_MENU_CLICKED).toBe('contextMenuClicked');
+    });
+  });
+});