Give the analytics overview a per-parent, per-year balance series

Each parent projection now carries one entry per calendar year from
birth to the fourth birthday: vacation earned, carried in, planned,
left, carried out and expiring under Semesterlagen's 20-day floor and
5-year carry-over, plus parental-leave days used and left at year end
with the age-4 clamp applied in the birthday year. The overview sums
them into per-year totals. Frontend types, mapper and fixtures follow.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XBRLomdLK9jF7wU7a8AA6H

backend/tests/conftest.py

@@ -337,9 +337,15 @@ async def analytics_service(
     child_repo: SQLiteChildRepository,
     personal_data_repo: SQLitePersonalDataRepository,
     workspace_repo: SQLiteWorkspaceRepository,
+    vacation_repo: SQLiteVacationDaysRepository,
 ) -> AnalyticsService:
     return AnalyticsService(
-        parental_leave_repo, planned_leave_repo, child_repo, personal_data_repo, workspace_repo
+        parental_leave_repo,
+        planned_leave_repo,
+        child_repo,
+        personal_data_repo,
+        workspace_repo,
+        vacation_repo,
     )