feat(fin,ops): Facturación y Cobranza (Diag. 4), bitácora de embarque (Diag. 3) y subida a MinIO

- schema fin: fin.invoices + fin.invoice_items + fin.payments; totales con IVA,
  estados borrador→emitida→enviada→pagada, cobranza (pagos) y saldo automático
- generar-factura-desde-embarque (toma conceptos de venta de la cotización)
- ops.shipment_events: bitácora/hitos del embarque con secuencia por defecto
  según operación (importación/exportación) — cubre Diagrama 3
- subida de documentos a MinIO: POST /crm/uploads (multipart) + URL firmada
- migración c4d5e6f7a8b9, routers/permisos (fin), seed del flujo hasta factura
- 58 tests pytest en verde

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/api/v1/modules/fin/invoices/models.py

@@ -0,0 +1,78 @@
+from datetime import date, datetime
+
+from sqlalchemy import Date, DateTime, ForeignKey, Integer, Numeric, String, Text, text
+from sqlalchemy.orm import Mapped, mapped_column
+
+from api.v1.common.base_models import TenantScopedMixin, TimestampMixin
+from core.database import Base
+
+
+class Invoice(Base, TenantScopedMixin, TimestampMixin):
+    """Factura (Diagrama 4). Integra los costos de la operación para cobro al cliente."""
+
+    __tablename__ = "invoices"
+    __table_args__ = {"schema": "fin"}
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
+    reference: Mapped[str | None] = mapped_column(String(40), nullable=True, index=True)  # folio
+    shipment_id: Mapped[int | None] = mapped_column(
+        Integer, ForeignKey("ops.shipments.id"), nullable=True, index=True
+    )
+    quote_id: Mapped[int | None] = mapped_column(
+        Integer, ForeignKey("crm.quotes.id"), nullable=True
+    )
+    account_id: Mapped[int | None] = mapped_column(
+        Integer, ForeignKey("crm.accounts.id"), nullable=True, index=True
+    )
+    currency: Mapped[str] = mapped_column(String(3), nullable=False, server_default=text("'MXN'"))
+    # borrador | emitida | enviada | pagada | cancelada
+    status: Mapped[str] = mapped_column(String(20), nullable=False, server_default=text("'borrador'"), index=True)
+    issue_date: Mapped[date | None] = mapped_column(Date, nullable=True)
+    due_date: Mapped[date | None] = mapped_column(Date, nullable=True)
+    subtotal: Mapped[float] = mapped_column(Numeric(14, 2), nullable=False, server_default=text("0"))
+    tax_rate: Mapped[float] = mapped_column(Numeric(5, 2), nullable=False, server_default=text("0"))  # % IVA
+    tax_amount: Mapped[float] = mapped_column(Numeric(14, 2), nullable=False, server_default=text("0"))
+    total: Mapped[float] = mapped_column(Numeric(14, 2), nullable=False, server_default=text("0"))
+    paid_amount: Mapped[float] = mapped_column(Numeric(14, 2), nullable=False, server_default=text("0"))
+    balance: Mapped[float] = mapped_column(Numeric(14, 2), nullable=False, server_default=text("0"))
+    bank_info: Mapped[str | None] = mapped_column(Text, nullable=True)  # datos bancarios
+    notes: Mapped[str | None] = mapped_column(Text, nullable=True)
+    sent_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    paid_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    owner_user_id: Mapped[str | None] = mapped_column(String(64), nullable=True, index=True)
+    created_by: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    updated_by: Mapped[str | None] = mapped_column(String(64), nullable=True)
+
+
+class InvoiceItem(Base, TenantScopedMixin, TimestampMixin):
+    """Concepto de una factura (transporte, flete, despacho, gastos en destino, otros)."""
+
+    __tablename__ = "invoice_items"
+    __table_args__ = {"schema": "fin"}
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
+    invoice_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("fin.invoices.id"), nullable=False, index=True
+    )
+    concept: Mapped[str] = mapped_column(String(60), nullable=False)
+    description: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    quantity: Mapped[float] = mapped_column(Numeric(12, 2), nullable=False, server_default=text("1"))
+    unit_amount: Mapped[float] = mapped_column(Numeric(14, 2), nullable=False, server_default=text("0"))
+
+
+class Payment(Base, TenantScopedMixin, TimestampMixin):
+    """Pago (cobranza) aplicado a una factura."""
+
+    __tablename__ = "payments"
+    __table_args__ = {"schema": "fin"}
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
+    invoice_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("fin.invoices.id"), nullable=False, index=True
+    )
+    amount: Mapped[float] = mapped_column(Numeric(14, 2), nullable=False)
+    payment_date: Mapped[date | None] = mapped_column(Date, nullable=True)
+    # transferencia | efectivo | cheque | tarjeta | otro
+    method: Mapped[str | None] = mapped_column(String(40), nullable=True)
+    reference: Mapped[str | None] = mapped_column(String(120), nullable=True)
+    notes: Mapped[str | None] = mapped_column(Text, nullable=True)