feat(amendment): soccorso istruttorio v3 — base dati + endpoint CRUD + internal BE

ROUND 1 della replica soccorso istruttorio speculare al BE Gepafin
bflows-bandi-be. Pacchetto base pronto, mancano scheduler/upload/email/FE
che vengono in round successivi.

==ARCHITETTURA DECISA CON CARLO==
- multi-tenancy lato BE: microservizio resta tenant-agnostic
- BE (bflows-bandi-be) fa polling sul nostro /internal e invia PEC/protocollo
  tenant-aware (hub=1 Gepafin PEC_SERVICE, hub=2 SviluppUmbria MAILGUN_SERVICE)
- microservizio NON fa PEC ne protocollo, NON conosce hub_id
- endpoint interni autenticati via shared secret X-Internal-Secret

==MIGRATION DB (2)==
mig 7: ALTER TABLE remission_amendment_request ADD
  response_days, extended_days, extension_date, internal_note,
  amendment_document_path/type, amendment_initial_document_path,
  response_document_path/type, protocol_id, email_log_id, user_action_id,
  pec_sent_at, pec_failed_reason, pec_retry_after
  + 2 index partial (status pec-pending, deadline scadenti)

mig 8: nuova tabella remission_expiration_config (type, interval_days,
  is_deleted) per reminder data-driven speculare a expiration_config BE.
  Seeded con (AMENDMENT, 7) e (AMENDMENT, 2).

==MODELLI==
- RemissionAmendmentRequest esteso con 13 colonne nuove
- RemissionExpirationConfig nuovo

==SCHEMAS==
- AmendmentStatus enum (DRAFT, AWAITING, RESPONSE_RECEIVED, EXPIRED, CLOSED)
- AmendmentRequestCreate esteso (response_days, internal_note)
- AmendmentRequestUpdate nuovo (solo DRAFT)
- AmendmentExtend nuovo (proroga)
- AmendmentPendingPecOut, AmendmentPecDetail (per BE polling)
- MarkPecSent, MarkPecFailed (callback BE)

==ENDPOINT ISTRUTTORE (estesi o nuovi)==
- POST /{pid}/amendment              crea DRAFT (modifica: non piu AWAITING diretto)
- PUT  /{pid}/amendment/{id}         modifica solo DRAFT [NUOVO]
- DELETE /{pid}/amendment/{id}       elimina solo DRAFT [NUOVO]
- POST /{pid}/amendment/{id}/send    DRAFT -> AWAITING [NUOVO]
- POST /{pid}/amendment/{id}/extend  proroga deadline [NUOVO]
- POST /{pid}/amendment/{id}/reminder reminder manuale (flag pec_retry_after) [NUOVO]
- POST /{pid}/amendment/{id}/close   chiude (AmendmentStatus enum al posto di stringhe)
- POST /{pid}/amendment/{id}/respond-beneficiary  benef risponde

==ENDPOINT INTERNI /internal/remission-amendments (nuovi)==
- GET     ?status=pending-pec|pending-reminder&since=
- GET     /{id}                        detail per composizione PEC
- POST    /{id}/mark-pec-sent          callback BE success
- POST    /{id}/mark-pec-failed        callback BE failure
Auth: X-Internal-Secret header, 401 altrimenti.

==CONFIG==
RENDIC_INTERNAL_SECRET env var (default sandbox hard-coded).

==TEST E2E==
/tmp/test_amendment_v3.py - 10 step tutti verdi:
  A reset T2 UNDER_REVIEW
  B create DRAFT (response_days=15 default)
  C update DRAFT (response_days=20, internal_note)
  D send DRAFT->AWAITING, pratica AWAITING_AMENDMENT
  E BE poll pending-pec vede amendment
  F BE detail+mark-pec-sent salva protocol_id/email_log_id/user_action_id
  G dopo mark-pec-sent scompare da pending-pec
  H benef respond -> RESPONSE_RECEIVED
  I istruttore close -> CLOSED, pratica torna UNDER_REVIEW
  AUTH internal senza secret -> 401

==NEXT (non in questo commit)==
- scheduler APScheduler cron 01:00 EXPIRED + cron 09:00 reminder
- upload amendment_document (istruttore) + response_document (benef) via files router
- template email locali non-PEC (reminder istruttore, notifica chiusura)
- UI istruttore: lista amendment + form crea/invia + proroga + reminder manuale
- UI benef: vista amendment + risposta con upload

app/models.py

@@ -235,12 +235,47 @@ class RemissionAmendmentRequest(Base):
     closed_at = Column(DateTime(timezone=True), nullable=True)
     closed_by = Column(Integer, nullable=True)
 
+    # soccorso v3: extended/document/PEC tracking
+    response_days = Column(Integer, nullable=True)
+    extended_days = Column(Integer, nullable=True)
+    extension_date = Column(DateTime(timezone=True), nullable=True)
+    internal_note = Column(Text, nullable=True)
+
+    amendment_document_path = Column(String(1024), nullable=True)
+    amendment_document_type = Column(String(128), nullable=True)
+    amendment_initial_document_path = Column(String(1024), nullable=True)
+
+    response_document_path = Column(String(1024), nullable=True)
+    response_document_type = Column(String(128), nullable=True)
+
+    # popolati dal BE via endpoint interni mark-pec-sent / mark-pec-failed
+    protocol_id = Column(String(128), nullable=True)
+    email_log_id = Column(Integer, nullable=True)
+    user_action_id = Column(Integer, nullable=True)
+    pec_sent_at = Column(DateTime(timezone=True), nullable=True)
+    pec_failed_reason = Column(Text, nullable=True)
+    pec_retry_after = Column(DateTime(timezone=True), nullable=True)
+
     created_at = Column(DateTime(timezone=True), nullable=False, server_default=func.now())
     updated_at = Column(DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now())
 
     practice = relationship("RemissionPractice", back_populates="amendment_requests")
 
 
+class RemissionExpirationConfig(Base):
+    """Config data-driven per reminder scadenze amendment (speculare a BE Gepafin
+    expiration_config). Ogni riga con type='AMENDMENT' e interval_days=N triggera
+    un reminder esattamente N giorni prima della scadenza. Multipli row = multipli reminder."""
+    __tablename__ = "remission_expiration_config"
+    __table_args__ = ({"schema": "gepafin_rendic"},)
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    type = Column(String(50), nullable=False)
+    interval_days = Column(Integer, nullable=False)
+    is_deleted = Column(Boolean, nullable=False, default=False)
+    created_at = Column(DateTime(timezone=True), nullable=False, server_default=func.now())
+
+
 class RemissionCustomCheckValue(Base):
     """Valore di un controllo custom configurato dallo schema del bando.
     Schema custom_checks[] nel template definisce code/label/description/requires_document/required.