- Introduced a new `RecurrencePattern` model to manage recurrence details for expenses, allowing for daily, weekly, monthly, and yearly patterns.
- Updated the `Expense` model to include fields for recurrence management, such as `is_recurring`, `recurrence_pattern_id`, and `next_occurrence`.
- Modified the database schema to reflect these changes, including alterations to existing columns and the removal of obsolete fields.
- Enhanced the expense creation logic to accommodate recurring expenses and updated related CRUD operations accordingly.
- Implemented necessary migrations to ensure database integrity and support for the new features.
