Phase 1: Fix TypeScript compilation — add missing API functions and fix hook signatures

- Add 8 missing API client functions (getBreakPeriods, createBreakPeriod, deleteBreakPeriod, getTips, getParentalLeave, getPlannedDays, createPlannedDay, deletePlannedDay)
- Fix useAnalytics to accept optional childId parameter
- Fix ApiError strict optional properties handling
- Export HeaderProps from Header component
- Update hook tests to use correct data structures and optional parameters

npx tsc --noEmit now passes with zero errors.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/src/hooks/useAnalytics.ts

@@ -9,17 +9,17 @@ interface UseAnalyticsResult {
   refresh: () => Promise<void>
 }
 
-export function useAnalytics(workspaceId: string | null): UseAnalyticsResult {
+export function useAnalytics(workspaceId: string | null, childId?: string): UseAnalyticsResult {
   const [data, setData] = useState<WorkspaceOverview | null>(null)
   const [isLoading, setIsLoading] = useState(false)
   const [error, setError] = useState<string | null>(null)
 
   const fetch = useCallback(async () => {
-    if (!workspaceId) return
+    if (!workspaceId || !childId) return
     setIsLoading(true)
     setError(null)
     try {
-      const response = await api.getWorkspaceOverview(workspaceId)
+      const response = await api.getWorkspaceOverview(workspaceId, childId)
       setData(response)
     } catch (err) {
       setError(err instanceof Error ? err.message : 'Failed to fetch analytics')
@@ -27,7 +27,7 @@ export function useAnalytics(workspaceId: string | null): UseAnalyticsResult {
     } finally {
       setIsLoading(false)
     }
-  }, [workspaceId])
+  }, [workspaceId, childId])
 
   useEffect(() => {
     fetch()