Link planned days to their wish, fix the age-4 cap, drop the planning goal

Three changes that together unblock treating a calendar period as one
editable object.

Migration 008 adds `planned_leave_day.wish_id` (nullable, ON DELETE SET NULL)
so a persisted day knows which `leave_wish` produced it, `is_pinned` to mark a
day the user hand-edited, and `leave_wish.target_days` so a period drawn on a
calendar need not be a whole number of weeks. Apply-time identity still keys on
day_type/is_dubbeldag only, so a wish_id-only difference is a metadata update
rather than a collision.

The age-4 savable ceiling was applying the per-child figure of 96 to each
parent's pool, modelling a two-parent family as able to save 192 days past the
child's fourth birthday. `resolve_age4_savable_cap` is now the single place
that decides 48 (couple with two parents) versus 96 (everyone else), and both
AnalyticsService and the allocator read it.

Migration 009 drops `workspace.planning_goal` and `leave_wish.goal_override`.
The allocator's tier-3 policy collapses to one rule; `salary_type` still
branches, since that reflects what a vacation day actually costs a parent
rather than a user preference.

frontend/src/services/api.ts

@@ -218,7 +218,6 @@ interface RawLeaveWish {
   priority: number
   parent_mode: 'either' | 'both' | 'specific'
   parent_personal_data_uuid: string | null
-  goal_override: 'max_time' | 'max_money' | 'balanced' | null
   window_mode: 'fixed' | 'flexible'
   created_at: string | null
   updated_at: string | null
@@ -242,7 +241,6 @@ function toLeaveWish(raw: RawLeaveWish): LeaveWish {
     priority: raw.priority,
     parentMode: raw.parent_mode,
     parentPersonalDataUuid: raw.parent_personal_data_uuid,
-    goalOverride: raw.goal_override,
     windowMode: raw.window_mode ?? 'fixed',
     createdAt: raw.created_at,
     updatedAt: raw.updated_at,
@@ -429,7 +427,6 @@ function toPersonalData(raw: RawPersonalData): PersonalData {
 interface RawWorkspace {
   id: string
   name: string
-  planning_goal: 'max_time' | 'max_money' | 'balanced'
   planning_mode: 'solo' | 'couple'
   created_at: string
 }
@@ -438,7 +435,6 @@ function toWorkspace(raw: RawWorkspace): Workspace {
   return {
     id: raw.id,
     name: raw.name,
-    planningGoal: raw.planning_goal,
     planningMode: raw.planning_mode,
     createdAt: raw.created_at,
   }
@@ -632,7 +628,6 @@ export async function updateWorkspace(
     method: 'PUT',
     body: JSON.stringify({
       name: req.name,
-      planning_goal: req.planningGoal,
       planning_mode: req.planningMode,
     }),
   })) as RawWorkspace
@@ -773,7 +768,6 @@ export async function createLeaveWish(payload: LeaveWishCreateRequest): Promise<
       priority: payload.priority ?? 1,
       parent_mode: payload.parentMode ?? 'either',
       parent_personal_data_uuid: payload.parentPersonalDataUuid ?? null,
-      goal_override: payload.goalOverride ?? null,
       window_mode: payload.windowMode ?? 'fixed',
     }),
   })) as RawLeaveWish
@@ -801,7 +795,6 @@ export async function updateLeaveWish(
   if (payload.parentPersonalDataUuid !== undefined) {
     body.parent_personal_data_uuid = payload.parentPersonalDataUuid
   }
-  if (payload.goalOverride !== undefined) body.goal_override = payload.goalOverride
   if (payload.windowMode !== undefined) body.window_mode = payload.windowMode
 
   const raw = (await apiFetch(`/leave-wishes/${id}`, {