Free days, vacation forfeiture, and global auto-replanning

Free days (Sat/Sun/red days, subject to DayOverride) can never be
vacation, and can only be parental leave when the workspace opts in via
take_pl_on_red_days. The allocator already honoured this; the hand-pin
path bypassed it entirely.

- PlanningService gains optional workspace_repo/day_override_repo deps
  and _reject_illegal_free_day, enforced in add_planned_day and update.
  Reuses allocation_service.is_free_day rather than re-deriving it, and
  no-ops when the deps are unset so existing callers are unaffected.
- update_planned_day had no ValidationError handler at all, so a
  validation failure there 500'd instead of 422'ing. Fixed.
- Calendar filters the pin write loop by the day's isFree; the modal
  explains free days stay off, and that pinning opts a day out of
  automatic re-planning.

Vacation days at risk of forfeiture were computed and sent over the
wire but never rendered: an at-risk column with the age-out/over-cap
split, and a dashboard key figure.

PlanProposal.warnings was likewise parsed but rendered nowhere, for all
three kinds. Adds PlanWarningCard in a Risks section above the tips,
with parent names resolved and dates formatted.

POST /api/plan/sync now fires from the workspace layer on every
plan-input change rather than only from Calendar, so a Settings edit or
a pinned-day save re-plans day types instead of merely refetching.
Overlapping bumps coalesce into one trailing run; a rejection cannot
wedge the in-flight guard. eviction_preview was silently dropped by the
frontend despite always being on the wire, and is now surfaced through
context.

Verified: backend 890 passed (91.49% coverage), frontend 1297 passed,
ruff/eslint/tsc clean. Browser-checked in Swedish and English.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JVQx4NUvPbJhn6UcvRd2QY

frontend/tests/fixtures/plan.ts

@@ -6,6 +6,8 @@
 import type {
   CostBreakdown,
   DayCollision,
+  EvictionCandidate,
+  EvictionPreview,
   PlanAge4Projection,
   PlanApplyResponse,
   PlanChange,
@@ -16,6 +18,7 @@ import type {
   ProposedDay,
   ProposedDayApplyItem,
   Rejection,
+  ResourceShortage,
   ShortfallRemedy,
   SurplusAdvice,
   VacationBalance,
@@ -202,11 +205,49 @@ export function makePlanChange(overrides: Partial<PlanChange> = {}): PlanChange
   }
 }
 
+export function makeEvictionCandidate(overrides: Partial<EvictionCandidate> = {}): EvictionCandidate {
+  return {
+    date: '2028-06-20',
+    parentPersonalDataUuid: 'pd-a',
+    childId: 'child-1',
+    dayType: 'vacation',
+    isDubbeldag: false,
+    wishId: 'lw-1',
+    wishName: 'Sommar',
+    ...overrides,
+  }
+}
+
+export function makeResourceShortage(overrides: Partial<ResourceShortage> = {}): ResourceShortage {
+  return {
+    resourceKind: 'vacation',
+    parentPersonalDataUuid: 'pd-a',
+    tier: null,
+    childId: null,
+    year: 2028,
+    daysEvicted: 1,
+    ...overrides,
+  }
+}
+
+/** Always present on `PlanSyncResponse`. Defaults to the common (nothing
+ * evicted) case — pass `{ wouldEvict: true, candidates: [...], shortages:
+ * [...] }` to build the "nothing was written, ask the user" case. */
+export function makeEvictionPreview(overrides: Partial<EvictionPreview> = {}): EvictionPreview {
+  return {
+    wouldEvict: false,
+    candidates: [],
+    shortages: [],
+    ...overrides,
+  }
+}
+
 export function makePlanSyncResponse(overrides: Partial<PlanSyncResponse> = {}): PlanSyncResponse {
   return {
     proposal: makePlanProposal(),
     applyResult: makePlanApplyResponse(),
     changes: [],
+    evictionPreview: makeEvictionPreview(),
     ...overrides,
   }
 }