Retrait des compétences ; disponibilités en fenêtres horaires libres

Compétences supprimées de bout en bout :
- tables `skill`, `volunteer_skill`, `shift_required_skill` ;
- `Volunteer.skill_codes`, `Shift.required_skill_codes`, colonne `skills`
  de l'import, règle de validation `MISSING_REQUIRED_SKILL`, jeu de démo.

Disponibilités repensées : `Availability` passe de (`day_part_id`,
`status` tri-état) à une **fenêtre horaire libre** (`date`, `start_time`,
`end_time` ; `end <= start` ⇒ passe minuit), plusieurs par jour.
- Nouveaux endpoints `GET`/`PUT /editions/{id}/volunteers/{vid}/availability`
  (PUT = remplacement complet, COORDINATION) et
  `GET /editions/{id}/availability` (toute l'édition, pour la grille).
- `OUTSIDE_AVAILABILITY` (toujours WARNING) : compare le créneau à l'union
  des fenêtres du bénévole ce jour-là ; renvoie `date` + `uncovered_minutes`.
  `DayPart` ne sert plus qu'à la borne de « journée » du cumul 8 h.
- L'import ne gère plus les disponibilités (fenêtres saisies dans l'app) :
  `values.py` supprimé, mapping réduit à nom/email/téléphone/commentaire.

Migration 0007 (recrée `availability`). `AvailabilityStatus` supprimé.
158 tests, `alembic check` et `ruff` au vert. Front à suivre.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017uUsRg7XzopkCPWimwg9ZM

backend/app/api/shifts.py

@@ -5,7 +5,7 @@ import uuid
 from fastapi import APIRouter, Depends, HTTPException, Response, status
 from sqlmodel import Session, select
 
-from app.api._common import owned_or_404, replace_links, resolve_skills
+from app.api._common import owned_or_404
 from app.api.deps import get_edition
 from app.api.schemas import ShiftCreate, ShiftRead, ShiftUpdate
 from app.auth.deps import (
@@ -15,44 +15,13 @@ from app.auth.deps import (
     require_staff,
 )
 from app.db import get_session
-from app.models import (
-    Account,
-    Edition,
-    Position,
-    Shift,
-    ShiftRequiredSkill,
-    Skill,
-)
+from app.models import Account, Edition, Position, Shift
 
 router = APIRouter(prefix="/editions/{edition_id}/shifts", tags=["shifts"])
 
 
-def _skill_codes(session: Session, shift_id: uuid.UUID) -> list[str]:
-    return sorted(
-        session.exec(
-            select(Skill.code)
-            .join(ShiftRequiredSkill, ShiftRequiredSkill.skill_id == Skill.id)
-            .where(ShiftRequiredSkill.shift_id == shift_id)
-        )
-    )
-
-
-def _read(session: Session, shift: Shift) -> ShiftRead:
-    return ShiftRead(
-        **shift.model_dump(),
-        required_skill_codes=_skill_codes(session, shift.id),
-    )
-
-
-def _set_skills(session: Session, shift: Shift, codes: list[str]) -> None:
-    skills = resolve_skills(session, shift.edition_id, codes)
-    replace_links(
-        session,
-        ShiftRequiredSkill,
-        filter_column=ShiftRequiredSkill.shift_id,
-        filter_value=shift.id,
-        pairs=[{"shift_id": shift.id, "skill_id": s.id} for s in skills],
-    )
+def _read(shift: Shift) -> ShiftRead:
+    return ShiftRead(**shift.model_dump())
 
 
 def _check_range(starts_at, ends_at) -> None:
@@ -84,16 +53,11 @@ def create_shift(
     _check_range(payload.starts_at, payload.ends_at)
     position = _require_position(session, payload.position_id, edition.id)
     ensure_can_write_position(account, position)
-    shift = Shift(
-        edition_id=edition.id,
-        **payload.model_dump(exclude={"required_skill_codes"}),
-    )
+    shift = Shift(edition_id=edition.id, **payload.model_dump())
     session.add(shift)
-    session.flush()
-    _set_skills(session, shift, payload.required_skill_codes)
     session.commit()
     session.refresh(shift)
-    return _read(session, shift)
+    return _read(shift)
 
 
 @router.get("", response_model=list[ShiftRead])
@@ -110,7 +74,7 @@ def list_shifts(
     )
     if position_id is not None:
         stmt = stmt.where(Shift.position_id == position_id)
-    return [_read(session, s) for s in session.exec(stmt)]
+    return [_read(s) for s in session.exec(stmt)]
 
 
 @router.get("/{shift_id}", response_model=ShiftRead)
@@ -121,7 +85,7 @@ def get_shift(
     session: Session = Depends(get_session),
 ) -> ShiftRead:
     shift = owned_or_404(session.get(Shift, shift_id), edition.id)
-    return _read(session, shift)
+    return _read(shift)
 
 
 @router.patch("/{shift_id}", response_model=ShiftRead)
@@ -135,18 +99,15 @@ def update_shift(
     shift = owned_or_404(session.get(Shift, shift_id), edition.id)
     ensure_can_write_shift(account, session, shift)
     changes = payload.model_dump(exclude_unset=True)
-    skill_codes = changes.pop("required_skill_codes", None)
     if "position_id" in changes:
         target = _require_position(session, changes["position_id"], edition.id)
         ensure_can_write_position(account, target)
     for field, value in changes.items():
         setattr(shift, field, value)
     _check_range(shift.starts_at, shift.ends_at)
-    if skill_codes is not None:
-        _set_skills(session, shift, skill_codes)
     session.commit()
     session.refresh(shift)
-    return _read(session, shift)
+    return _read(shift)
 
 
 @router.delete("/{shift_id}", status_code=status.HTTP_204_NO_CONTENT)