Étape 8 : connexion par mot de passe pour la coordination

Deux systèmes d'authentification, une même session JWT :
- COORDINATION : login e-mail + mot de passe (bcrypt), POST .../auth/login ;
  POST .../auth/change-password pour le compte courant
- RÉFÉRENTS / BÉNÉVOLES : lien magique inchangé, mais refusé pour un compte
  qui a un mot de passe

- Account.password_hash (nullable) + migration 0002 ; propriété auth_method
  ("password" / "magic_link") exposée dans AccountRead
- app/auth/passwords.py : hash/verify bcrypt, longueur mini 10
- Création de compte : password requis pour COORDINATOR, interdit sinon
- seed : la coordination de démo a un mot de passe, affiché dans le résumé
- 12 tests (login ok/ko, séparation des deux systèmes, change-password,
  validation à la création) ; 129 tests au total ; alembic check vert

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

backend/app/api/auth.py

@@ -1,4 +1,11 @@
-"""Endpoints d'authentification : lien magique, vérification, profil courant."""
+"""Authentification.
+
+Deux systèmes, selon le compte :
+- **mot de passe** (`POST .../auth/login`) pour les comptes qui en ont un —
+  la coordination ;
+- **lien magique** (`.../auth/magic-link` puis `.../auth/verify`) pour les
+  comptes sans mot de passe — référents et bénévoles.
+"""
 
 import datetime as dt
 import logging
@@ -10,11 +17,14 @@ from sqlmodel import Session, select
 
 from app.api.schemas import (
     AccountRead,
+    ChangePasswordRequest,
+    LoginRequest,
     MagicLinkRequest,
     TokenResponse,
     VerifyRequest,
 )
 from app.auth.deps import get_current_account
+from app.auth.passwords import MIN_LENGTH, hash_password, verify_password
 from app.auth.tokens import create_access_token, hash_token, new_raw_token
 from app.config import get_settings
 from app.db import get_session
@@ -24,6 +34,89 @@ router = APIRouter(tags=["auth"])
 logger = logging.getLogger("app.auth")
 
 
+def _account_by_email(
+    session: Session, edition_id: uuid.UUID, email: str
+) -> Account | None:
+    return session.exec(
+        select(Account)
+        .where(Account.edition_id == edition_id)
+        .where(func.lower(Account.email) == email.strip().lower())
+    ).first()
+
+
+def _issue(account: Account) -> TokenResponse:
+    return TokenResponse(
+        access_token=create_access_token(account),
+        token_type="bearer",
+        account=AccountRead.model_validate(account),
+    )
+
+
+def _invalid_credentials() -> HTTPException:
+    return HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail={"code": "auth.invalid_credentials"},
+    )
+
+
+def _invalid_token() -> HTTPException:
+    return HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail={"code": "auth.invalid_token"},
+    )
+
+
+# --------------------------------------------------------------------------- #
+# Mot de passe (admins)                                                        #
+# --------------------------------------------------------------------------- #
+@router.post("/editions/{edition_id}/auth/login", response_model=TokenResponse)
+def login(
+    edition_id: uuid.UUID,
+    payload: LoginRequest,
+    session: Session = Depends(get_session),
+) -> TokenResponse:
+    account = _account_by_email(session, edition_id, payload.email)
+    if (
+        account is None
+        or account.password_hash is None
+        or not verify_password(payload.password, account.password_hash)
+    ):
+        raise _invalid_credentials()
+    return _issue(account)
+
+
+@router.post(
+    "/editions/{edition_id}/auth/change-password",
+    status_code=status.HTTP_204_NO_CONTENT,
+)
+def change_password(
+    edition_id: uuid.UUID,
+    payload: ChangePasswordRequest,
+    account: Account = Depends(get_current_account),
+    session: Session = Depends(get_session),
+) -> None:
+    if account.edition_id != edition_id:
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail={"code": "error.forbidden"},
+        )
+    if account.password_hash is None or not verify_password(
+        payload.current_password, account.password_hash
+    ):
+        raise _invalid_credentials()
+    if len(payload.new_password) < MIN_LENGTH:
+        raise HTTPException(
+            status_code=422,
+            detail={"code": "auth.password_too_short", "min": MIN_LENGTH},
+        )
+    account.password_hash = hash_password(payload.new_password)
+    session.add(account)
+    session.commit()
+
+
+# --------------------------------------------------------------------------- #
+# Lien magique (référents, bénévoles)                                          #
+# --------------------------------------------------------------------------- #
 @router.post(
     "/editions/{edition_id}/auth/magic-link",
     status_code=status.HTTP_202_ACCEPTED,
@@ -33,14 +126,10 @@ def request_magic_link(
     payload: MagicLinkRequest,
     session: Session = Depends(get_session),
 ) -> dict[str, str]:
-    """Émet un lien magique si un compte correspond. Réponse identique dans
-    tous les cas (pas de divulgation de l'existence d'un compte)."""
-    account = session.exec(
-        select(Account)
-        .where(Account.edition_id == edition_id)
-        .where(func.lower(Account.email) == payload.email.strip().lower())
-    ).first()
-    if account is not None:
+    """Émet un lien magique si un compte **sans mot de passe** correspond.
+    Réponse identique dans tous les cas (pas de divulgation)."""
+    account = _account_by_email(session, edition_id, payload.email)
+    if account is not None and account.password_hash is None:
         raw = new_raw_token()
         token = MagicLinkToken(
             account_id=account.id,
@@ -78,24 +167,14 @@ def verify_magic_link(
         or token.used_at is not None
         or token.expires_at < local_now()
     ):
-        raise HTTPException(
-            status_code=status.HTTP_401_UNAUTHORIZED,
-            detail={"code": "auth.invalid_token"},
-        )
+        raise _invalid_token()
     account = session.get(Account, token.account_id)
     if account is None or account.edition_id != edition_id:
-        raise HTTPException(
-            status_code=status.HTTP_401_UNAUTHORIZED,
-            detail={"code": "auth.invalid_token"},
-        )
+        raise _invalid_token()
     token.used_at = local_now()
     session.commit()
     session.refresh(account)
-    return TokenResponse(
-        access_token=create_access_token(account),
-        token_type="bearer",
-        account=AccountRead.model_validate(account),
-    )
+    return _issue(account)
 
 
 @router.get("/auth/me", response_model=AccountRead)