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/components/layout/Header.tsx

@@ -1,6 +1,6 @@
 import { ReactNode } from 'react'
 
-interface HeaderProps {
+export interface HeaderProps {
   title?: string
   onLogout?: () => void
   onWorkspaceSelect?: () => void