feat(crm): módulo Tarifario — modelos, CRUD, import Excel y motor de costeo

- Tablas rate_sheets/lanes/breaks/charges (esquema crm) + migración con down().
- Catálogos nuevos: modo_tarifario, unidad_tarifa, concepto_cargo.
- CRUD de tarifarios y rutas; descarga de plantilla Excel por modo; import con
  vista previa y validación; alta directa desde Excel.
- Motor de costeo /rate-quote: aéreo (peso facturable + quiebres + optimización),
  marítimo FCL (por contenedor), LCL (W/M) y terrestre; suma cargos adicionales.

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

backend/api/v1/modules/crm/rates/models.py

@@ -0,0 +1,93 @@
+"""Modelos del módulo Tarifario (base de costos para Cotizaciones).
+
+Un ``RateSheet`` (tarifario) pertenece a un proveedor y agrupa muchas
+``RateLane`` (rutas origen→destino). Cada ruta tiene, según el modo:
+- Aéreo / LCL: varios ``RateBreak`` (quiebres de peso/volumen con su tarifa).
+- FCL / terrestre: una tarifa plana por contenedor/unidad (``flat_rate``).
+Los ``RateCharge`` son cargos adicionales a nivel tarifario o ruta.
+"""
+
+from datetime import date
+from decimal import Decimal
+
+from sqlalchemy import Date, 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 RateSheet(Base, TenantScopedMixin, TimestampMixin):
+    __tablename__ = "rate_sheets"
+    __table_args__ = {"schema": "crm"}
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
+    supplier_id: Mapped[int | None] = mapped_column(
+        Integer, ForeignKey("crm.suppliers.id"), nullable=True, index=True
+    )
+    # aereo | maritimo_fcl | maritimo_lcl | terrestre
+    mode: Mapped[str] = mapped_column(String(20), nullable=False, index=True)
+    name: Mapped[str] = mapped_column(String(255), nullable=False)
+    currency: Mapped[str | None] = mapped_column(String(3), nullable=True, server_default=text("'USD'"))
+    valid_from: Mapped[date | None] = mapped_column(Date, nullable=True)
+    valid_to: Mapped[date | None] = mapped_column(Date, nullable=True)
+    default_origin: Mapped[str | None] = mapped_column(String(20), nullable=True)
+    # borrador | activo | vencido | reemplazado
+    status: Mapped[str] = mapped_column(String(20), nullable=False, server_default=text("'borrador'"))
+    source_file: Mapped[str | None] = mapped_column(String(512), nullable=True)
+    source_url: Mapped[str | None] = mapped_column(String(1024), nullable=True)
+    notes: Mapped[str | None] = mapped_column(Text, nullable=True)
+    created_by: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    updated_by: Mapped[str | None] = mapped_column(String(64), nullable=True)
+
+
+class RateLane(Base, TenantScopedMixin, TimestampMixin):
+    __tablename__ = "rate_lanes"
+    __table_args__ = {"schema": "crm"}
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
+    rate_sheet_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("crm.rate_sheets.id"), nullable=False, index=True
+    )
+    origin: Mapped[str | None] = mapped_column(String(20), nullable=True, index=True)
+    destination: Mapped[str | None] = mapped_column(String(20), nullable=True, index=True)
+    region: Mapped[str | None] = mapped_column(String(60), nullable=True)
+    # Solo FCL/terrestre (código del catálogo tipo_equipo). Nulo en aéreo/LCL.
+    equipment_type: Mapped[str | None] = mapped_column(String(20), nullable=True)
+    # per_kg | per_wm | per_container | flat
+    rate_unit: Mapped[str | None] = mapped_column(String(20), nullable=True)
+    min_charge: Mapped[Decimal | None] = mapped_column(Numeric(14, 4), nullable=True)
+    flat_rate: Mapped[Decimal | None] = mapped_column(Numeric(14, 4), nullable=True)
+    transit_days: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    notes: Mapped[str | None] = mapped_column(Text, nullable=True)
+
+
+class RateBreak(Base, TenantScopedMixin, TimestampMixin):
+    __tablename__ = "rate_breaks"
+    __table_args__ = {"schema": "crm"}
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
+    rate_lane_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("crm.rate_lanes.id"), nullable=False, index=True
+    )
+    # Umbral del quiebre (kg en aéreo; W/M en LCL)
+    from_qty: Mapped[Decimal] = mapped_column(Numeric(12, 3), nullable=False, server_default=text("0"))
+    rate: Mapped[Decimal] = mapped_column(Numeric(14, 4), nullable=False, server_default=text("0"))
+
+
+class RateCharge(Base, TenantScopedMixin, TimestampMixin):
+    __tablename__ = "rate_charges"
+    __table_args__ = {"schema": "crm"}
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
+    rate_sheet_id: Mapped[int | None] = mapped_column(
+        Integer, ForeignKey("crm.rate_sheets.id"), nullable=True, index=True
+    )
+    rate_lane_id: Mapped[int | None] = mapped_column(
+        Integer, ForeignKey("crm.rate_lanes.id"), nullable=True, index=True
+    )
+    concept: Mapped[str] = mapped_column(String(60), nullable=False)
+    # fijo | por_kg | por_guia | por_contenedor | porcentaje
+    charge_type: Mapped[str] = mapped_column(String(20), nullable=False, server_default=text("'fijo'"))
+    value: Mapped[Decimal | None] = mapped_column(Numeric(14, 4), nullable=True)
+    condition: Mapped[str | None] = mapped_column(Text, nullable=True)