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

backend/app/repositories/planned_leave_repository.py

@@ -34,6 +34,16 @@ class PlannedLeaveRepository(Repository[PlannedLeaveDay]):
     async def count_dubbeldagar(self, child_id: UUID, from_date: date | None = None) -> int:
         """Count dubbeldagar already planned for a child (after from_date)."""
 
+    @abstractmethod
+    async def list_by_wish(self, wish_id: UUID) -> list[PlannedLeaveDay]:
+        """Every row currently attributed to this wish.
+
+        `LeaveWishService.delete()` reads this BEFORE `delete_by_wish` to
+        learn each row's (workspace, child, parent, date) key, so it can
+        clear any `DayAssertion` sitting at that key too — once the rows
+        are gone there is nothing left to look their keys up from.
+        """
+
     @abstractmethod
     async def delete_by_wish(self, wish_id: UUID) -> int:
         """Delete every row attributed to this wish (pinned or not) and return the count deleted.
@@ -65,11 +75,13 @@ class PlannedLeaveRepository(Repository[PlannedLeaveDay]):
         """
 
     @abstractmethod
-    async def update_metadata_many(self, pairs: list[tuple[UUID, UUID | None, bool]]) -> None:
-        """Bulk-update `(wish_id, is_pinned)` for existing rows via `executemany`.
+    async def update_metadata_many(self, pairs: list[tuple[UUID, UUID | None]]) -> None:
+        """Bulk-update `wish_id` for existing rows via `executemany`.
 
-        Each pair is `(id, wish_id, is_pinned)`. Does not touch `day_type`/
+        Each pair is `(id, wish_id)`. Does not touch `day_type`/
         `is_dubbeldag` — this is for the metadata-only path in
         `apply_proposed_days` (a row whose type is unchanged but whose
-        `wish_id`/`is_pinned` differ from the incoming batch).
+        `wish_id` differs from the incoming batch). `is_pinned` is not a
+        column on this entity any more (restructure step 3b, migration
+        010) — "pinned" is a `DayAssertion` fact now.
         """