feat: authentification QR code / token pour Pronote

Ajoute le mode d'authentification PRONOTE_AUTH_MODE=qr_token comme alternative
au mode password pour les instances Pronote utilisant HubEduConnect/EduConnect
où l'authentification par mot de passe échoue (CAPTCHA, MFA, flux SAML).

Nouveaux éléments :
- PronoteSettings : auth_mode, qr_code_file, qr_pin (SecretStr)
- PronoteAuthState : persistance du token rotatif dans .pronote_auth_state.json
  (écriture atomique, permissions 0600, symlink-safe via O_EXCL|O_NOFOLLOW)
- PronoteClient._connect_qr_token() : token_login avec creds persistés,
  qrcode_login pour l'enrôlement initial, export_credentials persisté après
  chaque login réussi
- PronoteAuthRotationError : levée en cas d'échec de rotation du token,
  propagée sans wrapping à travers PronoteFetcher et fetch_step jusqu'à
  PipelineRunner.run() qui notifie via XMPP (si canal disponible et dry_run inactif)
- _is_pronotepy_configured() mode-aware : qr_token ne requiert que PRONOTE_URL
- _collect_auth_secrets() : redaction des secrets explicites (token, PIN, jeton QR)
  dans tous les logs du chemin d'authentification

Documentation :
- .env.example : PRONOTE_AUTH_MODE, PRONOTE_QR_CODE_FILE, PRONOTE_QR_PIN
- AGENTS.md : contrat d'authentification QR code / token
- Wiki GuidePronote : section enrôlement, exécutions suivantes, ré-enrôlement

Tests (686 passés, couverture 94.87%) :
- 5 tests config QR, 9 tests auth_state, 10 tests client QR, 3 tests propagation,
  4 tests intégration rotation end-to-end, 4 tests fallback mode-aware
- Tests de non-fuite : sentinelles distinctes pour token, PIN, jeton QR

Co-authored-by: coder/litellm/coder <coder@agents.invalid>

tests/unit/test_rotation_propagation.py

@@ -0,0 +1,180 @@
+"""Unit tests for PronoteAuthRotationError propagation through each layer.
+
+These tests verify that the rotation error propagates correctly through the
+real call chain without being wrapped in PipelineCriticalError at any layer.
+"""
+
+from __future__ import annotations
+
+from datetime import date
+
+import pytest
+from pydantic import SecretStr
+
+from pronote_sync.config.settings import PronoteSettings, Settings
+from pronote_sync.errors import PipelineCriticalError, PronoteAuthRotationError
+from pronote_sync.models.agenda import Lesson, SchoolEvent
+from pronote_sync.models.homework import Homework
+from pronote_sync.models.message import Message
+from pronote_sync.pipeline.steps.fetch import fetch_step
+from pronote_sync.sources.pronote.fallback import PronoteFetcher
+
+
+class StubPronoteClientWithRotationError:
+    """Stub PronoteClient that raises PronoteAuthRotationError from its methods."""
+
+    def get_lessons(self, start: date, end: date) -> list[Lesson]:
+        """Raise rotation error when fetching lessons.
+
+        :param start: Start date (unused).
+        :param end: End date (unused).
+        :return: Never returns.
+        :raises PronoteAuthRotationError: Always.
+        """
+        del start, end
+        raise PronoteAuthRotationError("Token persisté expiré : ré-enrôlement requis")
+
+    def get_homeworks(self, start: date, end: date) -> list[Homework]:
+        """Raise rotation error when fetching homeworks.
+
+        :param start: Start date (unused).
+        :param end: End date (unused).
+        :return: Never returns.
+        :raises PronoteAuthRotationError: Always.
+        """
+        del start, end
+        raise PronoteAuthRotationError("Token persisté expiré : ré-enrôlement requis")
+
+    def get_messages(self) -> list[Message]:
+        """Return empty messages list.
+
+        :return: Empty list.
+        :rtype: list[Message]
+        """
+        return []
+
+    def get_informations(self) -> list[Message]:
+        """Return empty information messages list.
+
+        :return: Empty list.
+        :rtype: list[Message]
+        """
+        return []
+
+
+class StubSettings:
+    """Minimal settings stub for PronoteFetcher."""
+
+    def __init__(self) -> None:
+        """Initialize with minimal configuration."""
+        self.pronote = PronoteSettings(
+            url="https://pronote.example.com",
+            username="test",
+            password=SecretStr("test_password"),
+            ent="bordeaux",
+            account_type="parent",
+            agenda_source="pronotepy",
+            homework_source="pronotepy",
+            messages_source="pronotepy",
+            auth_mode="password",
+            qr_code_file=None,
+            qr_pin=None,
+            ical_url=None,
+        )
+        self.app = type("AppSettings", (), {"sync_past_days": 7, "sync_future_days": 7})()
+
+
+class StubFetcherWithRotationError:
+    """Stub PronoteFetcher that raises PronoteAuthRotationError from its methods."""
+
+    def __init__(self) -> None:
+        """Initialize the stub fetcher."""
+        self._settings = StubSettings()
+        self._client = StubPronoteClientWithRotationError()
+
+    def fetch_agenda(self) -> tuple[list[Lesson], list[SchoolEvent]]:
+        """Raise rotation error when fetching agenda.
+
+        :return: Never returns.
+        :rtype: tuple[list[Lesson], list[SchoolEvent]]
+        :raises PronoteAuthRotationError: Always.
+        """
+        raise PronoteAuthRotationError("Token persisté expiré : ré-enrôlement requis")
+
+    def fetch_homework(self, target_date: date) -> list[Homework]:
+        """Raise rotation error when fetching homework.
+
+        :param target_date: Target date (unused).
+        :return: Never returns.
+        :rtype: list[Homework]
+        :raises PronoteAuthRotationError: Always.
+        """
+        del target_date
+        raise PronoteAuthRotationError("Token persisté expiré : ré-enrôlement requis")
+
+    def fetch_messages(self) -> list[Message]:
+        """Return empty messages list.
+
+        :return: Empty list.
+        :rtype: list[Message]
+        """
+        return []
+
+    def fetch_informations(self) -> list[Message]:
+        """Return empty information messages list.
+
+        :return: Empty list.
+        :rtype: list[Message]
+        """
+        return []
+
+
+def test_pronote_fetcher_fetch_agenda_propagates_rotation_error() -> None:
+    """PronoteFetcher.fetch_agenda() propagates PronoteAuthRotationError without wrapping.
+
+    This test verifies that when the underlying PronoteClient raises
+    PronoteAuthRotationError, the fetcher propagates it directly without
+    converting it to PipelineCriticalError.
+    """
+    settings = Settings(pronote=StubSettings().pronote)
+    fetcher = PronoteFetcher(settings, StubPronoteClientWithRotationError())
+
+    with pytest.raises(PronoteAuthRotationError) as exc_info:
+        fetcher.fetch_agenda()
+
+    assert "Token persisté expiré" in str(exc_info.value)
+    assert not isinstance(exc_info.value, PipelineCriticalError)
+
+
+def test_pronote_fetcher_fetch_homework_propagates_rotation_error() -> None:
+    """PronoteFetcher.fetch_homework() propagates PronoteAuthRotationError without wrapping.
+
+    This test verifies that when the underlying PronoteClient raises
+    PronoteAuthRotationError, the fetcher propagates it directly without
+    converting it to PipelineCriticalError.
+    """
+    settings = Settings(pronote=StubSettings().pronote)
+    fetcher = PronoteFetcher(settings, StubPronoteClientWithRotationError())
+    target_date = date(2026, 9, 9)
+
+    with pytest.raises(PronoteAuthRotationError) as exc_info:
+        fetcher.fetch_homework(target_date)
+
+    assert "Token persisté expiré" in str(exc_info.value)
+    assert not isinstance(exc_info.value, PipelineCriticalError)
+
+
+def test_fetch_step_propagates_rotation_error() -> None:
+    """fetch_step() propagates PronoteAuthRotationError without wrapping.
+
+    This test verifies that the pipeline step fetch_step() propagates
+    PronoteAuthRotationError directly from the fetcher without converting
+    it to PipelineCriticalError.
+    """
+    fetcher = StubFetcherWithRotationError()
+
+    with pytest.raises(PronoteAuthRotationError) as exc_info:
+        fetch_step(fetcher, today=date(2026, 9, 8))
+
+    assert "Token persisté expiré" in str(exc_info.value)
+    assert not isinstance(exc_info.value, PipelineCriticalError)