feat: Budget feature enhancements

[khushi8112]

This PR focuses on refactoring and enhancing the Budget feature in ERPNext to make it more flexible, user-friendly, and closer to real-world budgeting scenarios.
The goal is to simplify the data structure, improve validation logic, and support multiple types of budget distributions and revisions.

• Refactor Budget data structure to simplify and improve usability.
• Merge Budget Accounts and Monthly Distribution into a unified design.
• Introduce support for quarterly, half-yearly, and yearly budget distributions.
• Add functionality to revise budgets within the defined project period.
• Enable multi-year budget allocation for long-running projects.
• Allow carry-forward of remaining budget to the next period.
• Add ability to reallocate or adjust budget across ledger accounts or dimensions.
• Support both percentage and fixed amount-based budget allocation.
• Add support for defining single budget across multiple accounting dimensions.
• Enable transfer of remaining budget between cost centers or projects.
• Improve validation logic to ensure real-time sync between allocated and distributed amounts.
• Add test cases to verify revised logic and data structure.
• Clean up UI/UX for better readability and navigation within the Budget form.