Track preschool planning days, partner invites and real vacation forfeiture

Three strands of work that grew together across the same settings screen and
API client, so they land as one change.

Per-year preschool planning days ("studiedagar"): new table, repository
(SQLite + Postgres), service, router and migration 007, plus the hooks and
Settings UI to plan and record them per child and year. Allocation now
reserves the recorded figure for a year where one exists and only falls back
to the child-level estimate otherwise, marking that fallback as assumed.

Partner invitations: workspaces issue and list invitations, registration
accepts an invite token to join the inviter's workspace instead of creating a
personal one, and a /join/:token page plus the settings invite panel drive it.

Vacation forfeiture: tips and the dashboard now distinguish days a parent
genuinely loses from days that merely age, so the warning stops firing on
balances that were never at risk.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/app/services/preschool_planning_days_service.py

@@ -0,0 +1,93 @@
+"""Business logic for per-year preschool planning ("studiedagar") days.
+
+The service owns the "no row yet" fallback: `child.preschool_planning_days_per_year`
+seeds `planned_days` the first time a year is touched (either a planned-days
+override or a taken-days record), so a caller never has to know whether a row
+already exists.
+
+NOTE for the allocation engine (`app/services/allocation_service.py`,
+`_preschool_reserve_days`): this service/table is not wired into it yet.
+That currently still multiplies `child.preschool_planning_days_per_year` by
+the number of years in the horizon. A follow-up should make it consume
+`PreschoolPlanningDaysRepository.list(child_id=...)` per year instead,
+falling back to the child default for years with no row (see
+`PreschoolPlanningDaysResponse.default_for`).
+"""
+
+from datetime import datetime
+from uuid import UUID, uuid4
+
+from app.entities.child import Child
+from app.entities.preschool_planning_days import PreschoolPlanningDays
+from app.repositories.preschool_planning_days_repository import (
+    PreschoolPlanningDaysRepository,
+)
+from app.utils.errors import NotFoundError, ValidationError
+
+
+class PreschoolPlanningDaysService:
+    def __init__(self, repo: PreschoolPlanningDaysRepository) -> None:
+        self._repo = repo
+
+    async def upsert_planned(
+        self, child: Child, year: int, planned_days: int
+    ) -> PreschoolPlanningDays:
+        """Create or update the planned-days figure for (child, year).
+
+        Preserves any already-recorded `taken_days`.
+        """
+        if planned_days < 0:
+            raise ValidationError("Planned days cannot be negative")
+
+        existing = await self._repo.get_by_child_year(child.id, year)
+        if existing is not None:
+            existing.planned_days = planned_days
+            return await self._repo.update(existing.id, existing)
+
+        entity = PreschoolPlanningDays(
+            id=uuid4(),
+            child_id=child.id,
+            year=year,
+            planned_days=planned_days,
+            taken_days=None,
+            created_at=datetime.now(),
+            updated_at=datetime.now(),
+        )
+        return await self._repo.create(entity)
+
+    async def record_taken(self, child: Child, year: int, taken_days: int) -> PreschoolPlanningDays:
+        """Record how many planning days were actually taken for (child, year).
+
+        Seeds `planned_days` from `child.preschool_planning_days_per_year` if
+        no row exists yet.
+        """
+        if taken_days < 0:
+            raise ValidationError("Taken days cannot be negative")
+
+        existing = await self._repo.get_by_child_year(child.id, year)
+        if existing is not None:
+            existing.taken_days = taken_days
+            return await self._repo.update(existing.id, existing)
+
+        entity = PreschoolPlanningDays(
+            id=uuid4(),
+            child_id=child.id,
+            year=year,
+            planned_days=child.preschool_planning_days_per_year,
+            taken_days=taken_days,
+            created_at=datetime.now(),
+            updated_at=datetime.now(),
+        )
+        return await self._repo.create(entity)
+
+    async def get_by_child_year(self, child_id: UUID, year: int) -> PreschoolPlanningDays | None:
+        return await self._repo.get_by_child_year(child_id, year)
+
+    async def get(self, entry_id: UUID, child_id: UUID | None = None) -> PreschoolPlanningDays:
+        entity = await self._repo.get_by_id(entry_id)
+        if entity is None or (child_id is not None and entity.child_id != child_id):
+            raise NotFoundError(f"PreschoolPlanningDays {entry_id} not found")
+        return entity
+
+    async def list_for_child(self, child_id: UUID) -> list[PreschoolPlanningDays]:
+        return await self._repo.list(child_id=child_id)