Fixes: 1) Correct default manager assignment in `Product` model; 2) Address potential division by zero in `AbsoluteFTPStorage`; 3) Ensure proper exception handling for missing `order` attributes in CRM gateway methods; 4) Rectify inaccurate string formatting for `Transaction` `__str__` method.
Extra: Refactor various minor code style issues, including formatting corrections in the README, alignment in the emailing utility, and suppressed pycharm-specific inspections; clean up unused imports across files; enhance error messaging consistency.
Fixes: 1) Correct provider name from "amo" to "AmoCRM";
Extra: 1) Remove unused `time` import and redundant token caching logic; 2) Add missing CRMException import to signals; 3) Minor code cleanup and readability improvements;
Fixes: 1) Simplify retrieval of `OrderCrmLink` to use `get()` instead of `filter().first()`; 2) Eliminate redundant `Order` lookup by utilizing `link.order`.
Extra: Refactored code to enhance readability and efficiency in status update logic.
Fixes: 1) Improve validation logic to ensure only one default CRM provider within the model.
Extra: 1) Replace CRM object string representation to use `name` instead of `crm_lead_id`; 2) Refactor token caching to improve reliability and readability.
Fixes: 1) Resolved malformed phone number issue in serializer when `instance` is unavailable; 2) Corrected relation field naming for `OrderCrmLink` (`order_uuid` to `order`); 3) Ensured only one default CRM provider can exist.
Extra: 1) Refactored `is_business` logic with error handling; 2) Improved logging for CRM integration errors; 3) Added `integration_location` and `default` fields to CRM configuration model.
