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/store/index.ts

@@ -33,6 +33,22 @@ export type { MemoryGraphStore, GraphNode, GraphEdge, GraphFilter, GraphLayout }
 export { useActiveLearningStore } from './activeLearningStore';
 export type { ActiveLearningStore } from './activeLearningStore';
 
+// === Browser Hand Store ===
+export { useBrowserHandStore } from './browserHandStore';
+export type {
+  BrowserHandState,
+  BrowserHandActions,
+  ExecutionState,
+  ExecutionStatus,
+  BrowserSession,
+  SessionStatus,
+  BrowserLog,
+  LogLevel,
+  RecentTask,
+  TaskResultStatus,
+  SessionOptions,
+} from '../components/BrowserHand/templates/types';
+
 // === Composite Store Hook ===
 
 import { useMemo } from 'react';