feat(crm): PDF de cotización (formato maestro) + marca por tenant + envío por correo

- Modelo crm.quote_settings (emisor, logo, color, prefijo, términos) por compañía
  + columna quotes.pdf_file_key + migración con down().
- Generador PDF (formato maestro: emisor+logo, cliente, carga/ruta, costos,
  resumen, condiciones); logo incrustado como JPEG (Pillow).
- Endpoints: GET /quotes/{id}/pdf-url, POST /quotes/{id}/send-email (adjunta PDF),
  GET/PUT /quote-settings, POST /quote-settings/logo.

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

backend/api/v1/modules/crm/quotes/dto.py

@@ -86,6 +86,7 @@ class QuoteResponse(QuoteBase):
     status: str
     total_cost: Decimal
     total_sale: Decimal
+    pdf_file_key: str | None = None
     sent_at: datetime | None = None
     accepted_at: datetime | None = None
     rejected_at: datetime | None = None
@@ -100,3 +101,30 @@ class QuoteResponse(QuoteBase):
     @property
     def margin(self) -> Decimal:
         return (self.total_sale or Decimal(0)) - (self.total_cost or Decimal(0))
+
+
+# ----- Configuración de marca del formato de cotización -----
+
+class QuoteSettingsInput(BaseModel):
+    emitter_name: str | None = Field(None, max_length=255)
+    emitter_rfc: str | None = Field(None, max_length=13)
+    emitter_address: str | None = None
+    emitter_phone: str | None = Field(None, max_length=60)
+    emitter_email: str | None = Field(None, max_length=255)
+    emitter_website: str | None = Field(None, max_length=255)
+    accent_color: str | None = Field(None, max_length=9)
+    quote_prefix: str | None = Field(None, max_length=12)
+    default_terms: str | None = None
+    footer_note: str | None = None
+
+
+class QuoteSettingsResponse(QuoteSettingsInput):
+    model_config = ConfigDict(from_attributes=True)
+    id: int | None = None
+    logo_file_key: str | None = None
+
+
+class SendQuoteEmailRequest(BaseModel):
+    to: str | None = None
+    subject: str | None = None
+    message: str | None = None