Refactor/remove dead code

[austin047]

Description

Removes the death code and includes agent.md to assist with AI code generation

Type of Change

• [] ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[sourceant]

Code Review Summary

This PR focuses on cleaning up dead code in the budget module, specifically removing remote-fetch logic for budget progress and transactions in favor of a local-first recomputation model. It also adds an AGENTS.md guide to maintain architecture standards.

🚀 Key Improvements

• Simplified BudgetCubit by removing unused state flags and methods.
• Eliminated several dead DTOs and UseCases (FetchBudgetProgressUseCase, FetchBudgetTransactionsUseCase).
• Established a clear 'Architecture Layering Rule' in the new documentation.

💡 Minor Suggestions

• Remove commented-out code blocks in budget_remote_datasource.dart instead of just commenting them.
• Verify pubspec.lock version downgrades.

[sourceant]

Review complete. See the overview comment for a summary.

[sourceant]

The import of enums.dart was moved within the import block, but usually, it's better to keep package imports sorted alphabetically and separate from project-relative imports. However, here it's fine, but ensure the enums.dart is actually needed by the remaining code in this file.

Suggested change

	import 'package:trakli/presentation/utils/dialogs.dart'
	import 'package:trakli/presentation/utils/enums.dart';
	import 'package:trakli/presentation/utils/dialogs.dart'
	show showDeleteConfirmationDialog, showConfirmationDialog;