feat: deliverables 3-6 — cold start, simple mode UI, bridge tests, docs

Deliverable 3 — Cold Start Flow:
- New: use-cold-start.ts — cold start detection + greeting management
- Default Chinese greeting for hospital admin users
- Phase tracking: idle → greeting_sent → waiting_response → completed

Deliverable 4 — Simple Mode UI:
- New: uiModeStore.ts — 'simple'|'professional' mode with localStorage
- New: SimpleTopBar.tsx — minimal top bar with mode toggle
- Modified: App.tsx — dual layout rendering based on UI mode
- Modified: ChatArea.tsx — compact prop hides advanced controls
- Default: 'simple' mode for zero-barrier first experience

Deliverable 5 — Tauri Bridge Integration Tests:
- New: tauri-bridge.integration.test.ts — 14 test cases
- Covers: cold start, chat flow, persistence, memory, butler, UI mode, e2e
- 14/14 passing

Deliverable 6 — Release Documentation:
- New: installation-guide.md — user-facing install guide (Chinese, no jargon)
- New: hospital-deployment.md — IT admin deployment guide (Docker, GPO, SCCM)

desktop/src/store/uiModeStore.ts

@@ -0,0 +1,91 @@
+/**
+ * uiModeStore.ts - UI Mode Management Store
+ *
+ * Manages the toggle between simple mode and professional mode.
+ * Persists preference to localStorage.
+ */
+
+import { create } from 'zustand';
+import { createLogger } from '../lib/logger';
+
+const log = createLogger('uiModeStore');
+
+// === Types ===
+
+export type UIMode = 'simple' | 'professional';
+
+export interface UIModeState {
+  mode: UIMode;
+  setMode: (mode: UIMode) => void;
+  toggleMode: () => void;
+}
+
+// === Constants ===
+
+const UI_MODE_STORAGE_KEY = 'zclaw-ui-mode';
+const DEFAULT_MODE: UIMode = 'simple';
+
+// === Persistence Helpers ===
+
+function loadStoredMode(): UIMode {
+  try {
+    const stored = localStorage.getItem(UI_MODE_STORAGE_KEY);
+    if (stored === 'simple' || stored === 'professional') {
+      return stored;
+    }
+  } catch (err) {
+    log.warn('Failed to read UI mode from localStorage:', err);
+  }
+  return DEFAULT_MODE;
+}
+
+function persistMode(mode: UIMode): void {
+  try {
+    localStorage.setItem(UI_MODE_STORAGE_KEY, mode);
+  } catch (err) {
+    log.warn('Failed to persist UI mode:', err);
+  }
+}
+
+// === Store ===
+
+export const useUIModeStore = create<UIModeState>((set, get) => ({
+  mode: loadStoredMode(),
+
+  setMode: (mode: UIMode) => {
+    const current = get().mode;
+    if (current === mode) return;
+
+    persistMode(mode);
+    set({ mode });
+    log.debug('UI mode changed:', mode);
+  },
+
+  toggleMode: () => {
+    const current = get().mode;
+    const next: UIMode = current === 'simple' ? 'professional' : 'simple';
+
+    persistMode(next);
+    set({ mode: next });
+    log.debug('UI mode toggled:', current, '->', next);
+  },
+}));
+
+// === Non-hook Accessors ===
+
+/**
+ * Get current UI mode without React hook.
+ */
+export const getUIMode = (): UIMode => useUIModeStore.getState().mode;
+
+/**
+ * Check if current mode is simple.
+ */
+export const isSimpleMode = (): boolean => useUIModeStore.getState().mode === 'simple';
+
+/**
+ * Check if current mode is professional.
+ */
+export const isProfessionalMode = (): boolean => useUIModeStore.getState().mode === 'professional';
+
+export default useUIModeStore;