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.test.ts

@@ -188,7 +188,6 @@ describe('API response mappers (snake_case → camelCase)', () => {
           priority: 1,
           parent_mode: 'either',
           parent_personal_data_uuid: null,
-          goal_override: null,
           created_at: '2026-06-14T17:09:47',
           updated_at: '2026-06-14T17:09:47',
         },
@@ -265,7 +264,6 @@ describe('API response mappers (snake_case → camelCase)', () => {
         priority: 1,
         parent_mode: 'either',
         parent_personal_data_uuid: null,
-        goal_override: null,
         created_at: '2026-06-14T17:09:47',
         updated_at: '2026-06-14T17:09:47',
       }
@@ -322,7 +320,6 @@ describe('API response mappers (snake_case → camelCase)', () => {
         priority: 1,
         parent_mode: 'either',
         parent_personal_data_uuid: null,
-        goal_override: null,
         created_at: '2026-06-14T17:09:47',
         updated_at: '2026-06-14T17:09:47',
       }
@@ -361,7 +358,7 @@ describe('API response mappers (snake_case → camelCase)', () => {
       const rawResponse = {
         id: 'ws1',
         name: 'My Workspace',
-        planning_goal: 'max_time' as const,
+        planning_mode: 'couple' as const,
         created_at: '2026-06-14T17:09:47',
       }
 
@@ -375,7 +372,7 @@ describe('API response mappers (snake_case → camelCase)', () => {
 
       expect(result.id).toBe('ws1')
       expect(result.name).toBe('My Workspace')
-      expect(result.planningGoal).toBe('max_time')
+      expect(result.planningMode).toBe('couple')
       expect(result.createdAt).toBe('2026-06-14T17:09:47')
     })
   })
@@ -666,7 +663,6 @@ describe('endpoint functions (representative coverage)', () => {
       json: async () => ({
         id: 'ws1',
         name: 'Home',
-        planning_goal: 'balanced',
         planning_mode: 'solo',
         created_at: '2026-01-01',
       }),
@@ -685,7 +681,6 @@ describe('endpoint functions (representative coverage)', () => {
       json: async () => ({
         id: 'ws1',
         name: 'New name',
-        planning_goal: 'max_money',
         planning_mode: 'couple',
         created_at: '2026-01-01',
       }),
@@ -693,17 +688,14 @@ describe('endpoint functions (representative coverage)', () => {
 
     const result = await api.updateWorkspace('ws1', {
       name: 'New name',
-      planningGoal: 'max_money',
       planningMode: 'couple',
     })
 
     expect(lastRequest()).toEqual({ url: '/api/workspace/ws1', method: 'PUT' })
     expect(lastRequestBody()).toEqual({
       name: 'New name',
-      planning_goal: 'max_money',
       planning_mode: 'couple',
     })
-    expect(result.planningGoal).toBe('max_money')
     expect(result.planningMode).toBe('couple')
   })
 
@@ -871,7 +863,6 @@ describe('endpoint functions (representative coverage)', () => {
         priority: 1,
         parent_mode: 'either',
         parent_personal_data_uuid: null,
-        goal_override: null,
         created_at: '2026-01-01',
         updated_at: '2026-01-01',
       }),
@@ -908,7 +899,6 @@ describe('endpoint functions (representative coverage)', () => {
         priority: 1,
         parent_mode: 'either',
         parent_personal_data_uuid: null,
-        goal_override: null,
         created_at: '2026-01-01',
         updated_at: '2026-01-01',
       }),
@@ -944,7 +934,6 @@ describe('endpoint functions (representative coverage)', () => {
         priority: 2,
         parent_mode: 'specific',
         parent_personal_data_uuid: 'pd1',
-        goal_override: 'max_time',
         window_mode: 'fixed',
         created_at: '2026-01-01',
         updated_at: '2026-01-01',
@@ -965,7 +954,6 @@ describe('endpoint functions (representative coverage)', () => {
       priority: 2,
       parentMode: 'specific',
       parentPersonalDataUuid: 'pd1',
-      goalOverride: 'max_time',
     })
 
     expect(lastRequestBody()).toEqual({
@@ -982,7 +970,6 @@ describe('endpoint functions (representative coverage)', () => {
       priority: 2,
       parent_mode: 'specific',
       parent_personal_data_uuid: 'pd1',
-      goal_override: 'max_time',
     })
   })
 
@@ -1009,7 +996,6 @@ describe('endpoint functions (representative coverage)', () => {
         priority: 1,
         parent_mode: 'either',
         parent_personal_data_uuid: null,
-        goal_override: null,
         window_mode: 'flexible',
         created_at: '2026-01-01',
         updated_at: '2026-01-01',
@@ -1053,7 +1039,6 @@ describe('endpoint functions (representative coverage)', () => {
         priority: 1,
         parent_mode: 'either',
         parent_personal_data_uuid: null,
-        goal_override: null,
         window_mode: 'fixed',
         created_at: '2026-01-01',
         updated_at: '2026-01-01',
@@ -1095,7 +1080,6 @@ describe('endpoint functions (representative coverage)', () => {
         priority: 1,
         parent_mode: 'either',
         parent_personal_data_uuid: null,
-        goal_override: null,
         window_mode: 'flexible',
         created_at: '2026-01-01',
         updated_at: '2026-01-01',