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/tests/unit/test_planning_service_apply.py

@@ -257,13 +257,17 @@ class TestApplyProposedDaysCollisions:
 
 
 class TestApplyProposedDaysWishAttribution:
-    """`wish_id`/`is_pinned` are new fields on `ProposedDayInput` — the
-    keystone that lets the UI later click a multi-day band on the calendar
-    and edit it as one period. This covers them surviving the write path and
-    the "metadata-only update" carve-out from the collision rules.
+    """`wish_id` is a field on `ProposedDayInput` — the keystone that lets
+
+    the UI later click a multi-day band on the calendar and edit it as one
+    period. This covers it surviving the write path and the "metadata-only
+    update" carve-out from the collision rules. `is_pinned` is no longer a
+    field here (restructure step 3b) — a freshly-applied day is never
+    pinned on its own; see `test_day_assertion.py` for that half of what
+    this test used to also cover.
     """
 
-    async def test_wish_id_and_is_pinned_survive_create(
+    async def test_wish_id_survives_create(
         self,
         planning_service: PlanningService,
         planned_leave_repo: SQLitePlannedLeaveRepository,
@@ -284,7 +288,6 @@ class TestApplyProposedDaysWishAttribution:
                 child,
                 "vacation",
                 wish_id=wish_id,
-                is_pinned=True,
             ),
         ]
 
@@ -293,14 +296,12 @@ class TestApplyProposedDaysWishAttribution:
         assert result.accepted is True
         assert result.created_count == 1
         assert result.created[0].wish_id == wish_id
-        assert result.created[0].is_pinned is True
 
         rows = await planned_leave_repo.list_by_workspace_child(
             workspace_id=ws, child_id=child, from_date=date(2026, 6, 1), to_date=date(2026, 6, 30)
         )
         assert len(rows) == 1
         assert rows[0].wish_id == wish_id
-        assert rows[0].is_pinned is True
 
     async def test_ad_hoc_day_has_no_wish_id(
         self,
@@ -318,7 +319,6 @@ class TestApplyProposedDaysWishAttribution:
         result = await planning_service.apply_proposed_days(ws, days)
 
         assert result.created[0].wish_id is None
-        assert result.created[0].is_pinned is False
 
     async def test_reapply_with_different_wish_id_updates_attribution_not_collision(
         self,