feat(browser-hand): implement Browser Hand UI components

Add complete Browser Hand UI system for browser automation:

Components:
- BrowserHandCard: Main card with status display and screenshot preview
- TaskTemplateModal: Template selection and parameter configuration
- ScreenshotPreview: Screenshot display with fullscreen capability

Templates:
- Basic operations: navigate, screenshot, form fill, click, execute JS
- Scraping: text, list, images, links, tables
- Automation: login+action, multi-page, monitoring, pagination

Features:
- 15 built-in task templates across 3 categories
- Real-time execution status with progress bar
- Screenshot preview with zoom and fullscreen
- Integration with HandsPanel for seamless UX
- Zustand store for state management
- Comprehensive test coverage (16 tests)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktop/src/components/BrowserHand/index.ts

@@ -0,0 +1,42 @@
+/**
+ * BrowserHand Module
+ *
+ * Exports all Browser Hand components and utilities.
+ */
+
+// Components
+export { BrowserHandCard } from './BrowserHandCard';
+export { TaskTemplateModal } from './TaskTemplateModal';
+export { ScreenshotPreview } from './ScreenshotPreview';
+
+// Templates
+export {
+  BUILTIN_TEMPLATES,
+  templateRegistry,
+  validateTemplateParams,
+  mergeParamsWithDefaults,
+  getTemplate,
+  getTemplatesByCategory,
+  getAllTemplates,
+  registerTemplate,
+} from './templates';
+
+// Types
+export type {
+  TaskTemplate,
+  TaskTemplateParam,
+  TemplateCategory,
+  ExecutionContext,
+  ExecutionState,
+  ExecutionStatus,
+  BrowserSession,
+  SessionStatus,
+  BrowserLog,
+  LogLevel,
+  RecentTask,
+  TaskResultStatus,
+  SessionOptions,
+  ValidationError,
+  ValidationResult,
+  TemplateRegistry,
+} from './templates';