Separate user intent from planner output via day assertions

The calendar mixed two kinds of truth in one table. `planned_leave_day` was
simultaneously the allocator's output cache, the user's override store
(`is_pinned`, plus ad-hoc rows with no `wish_id`), and the resource ledger that
analytics and the age-4 maths read. The planner therefore had to ask "am I
allowed to touch this row?" on every sync, and got it wrong at the edges.

Every user assertion is now one `day_assertion` row — a concrete `day_type`
replaces a pinned day, a row with no `wish_id` replaces an ad-hoc day, and
`day_type='none'` replaces `planned_day_exclusion`. `planned_leave_day` becomes
purely derived with a single writer, and `PlanningService.pinned_keys()` is the
single answer to "is this day pinned", used by the allocator's loader, by
`sync_plan` and by the read router alike.

On top of that, every calendar band is now a real event: an ad-hoc band opens
the same full editor as a wish-backed one and saving it promotes it to a
`LeaveWish`, so it can be named, repeated yearly, assigned to either or both
parents, and handed to the planner. "Planering" is a `moveable` toggle plus a
from/to month bound plus a separate lock/unlock action on the days themselves,
replacing a three-rung ladder whose "planner decides" rung set a search window
equal to the drawn dates and so could never move anything.

Bugs found and fixed along the way:

- The plan erased its own history. Fixed windows clip to today, so an elapsed
  auto-placed day fell into `stale_keys` and was deleted on the next sync —
  and a background sync runs on every workspace load. Past rows are now frozen
  and counted as spent.
- Migration 010's downgrade silently destroyed every pinned day and exclusion
  (`is_pinned` returned as DEFAULT 0, the exclusion table came back empty,
  exit 0, no warning). It now reconstructs both from `day_assertion`, and 009
  itemises what it cannot recover before dropping the table.
- Deleting a period left its assertions behind, locking those dates forever
  with no UI path to clear them. Wish deletion now clears them by `wish_id`.
- `DayAssertionService` and `LeaveWishService` committed multi-statement writes
  without a transaction; a crash mid-write diverged the tables or half-deleted
  a series. Both now run in a unit of work.
- A sibling year's shortfall was never surfaced: the toast only inspected the
  edited occurrence's outcome, so a fully unfunded later year rendered as an
  empty band with no warning.
- A flexible window whose bound had entirely elapsed was dropped from the
  proposal with no outcome at all. It now reports as `unplaced`.
- Unlocking a period deleted its days instead of returning them to the planner.
- The e2e global setup posted to a route deleted in this change, which would
  have failed the whole suite before its first test.

Gates: backend 938 tests / 91% coverage, frontend 1351 / 97.4 | 92.2 | 94.37 |
97.4. Migrations 009 and 010 audited against a hand-built realistic database:
the upgrade reconciles exactly and a constraint violation fails safe, leaving
the schema at 008.

Not complete. Step 4's toggle, month picker and lock/unlock action are verified
by browser walk and unit tests, but the partial-lock readout was not exercised.
`ideas.md` §7 adds a full plan for the vacation-forfeiture defect (the planner
detects expiring days and then does nothing about them) — not implemented here.
Remaining smaller items are listed in the session's restructure notes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T4wjgbVL4HAC5Rdaw75VbV

frontend/e2e/support/api.ts

@@ -75,7 +75,7 @@ export async function apiGetContext(token: string): Promise<ApiUserContext> {
 
 export type PlannedDayType = 'sjukpenning' | 'lagsta' | 'vacation'
 
-export interface PlannedDayPayload {
+export interface DayAssertionPayload {
   workspace_id: string
   child_id: string
   parent_personal_data_uuid: string
@@ -84,14 +84,19 @@ export interface PlannedDayPayload {
   is_dubbeldag: boolean
 }
 
-export async function apiCreatePlannedDay(token: string, payload: PlannedDayPayload): Promise<void> {
-  const res = await fetch(`${API_BASE}/api/planned-days`, {
+// `/api/planned-days` is read-only (restructure step 3b) — every write goes
+// through `POST /api/day-assertions` instead, which mirrors a concrete
+// assertion straight into `planned_leave_day` (see
+// `app/services/day_assertion_service.py`), so this still materializes a
+// band the calendar renders immediately.
+export async function apiAssertDay(token: string, payload: DayAssertionPayload): Promise<void> {
+  const res = await fetch(`${API_BASE}/api/day-assertions`, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${token}` },
     body: JSON.stringify(payload),
   })
   if (!res.ok) {
-    throw new Error(`create planned day ${payload.date} failed: ${res.status} ${await res.text()}`)
+    throw new Error(`assert day ${payload.date} failed: ${res.status} ${await res.text()}`)
   }
 }