This reverts commit de4bc6fa70d6bda5d3ce1fc42f6cd784d9c774d4.

- Updated tests to use NOTELEAF_CONFIG and NOTELEAF_DATA_DIR environment variables instead of XDG_CONFIG_HOME.
- getEditor method in NoteHandler prioritizes config settings over environment variables.
- Modified LoadConfig and SaveConfig functions to respect NOTELEAF_CONFIG for custom configuration paths.
- Implemented GetDataDir function to handle NOTELEAF_DATA_DIR for data directory management.
- Adjusted database initialization to utilize new configuration paths and ensure directory creation.
- Improved error handling in database operations and ensured proper cleanup in tests.

- Updated task handler tests to include interactive mode paths with and without filters.
- Refactored note handler tests to support interactive mode, including tests for filtering by tags.
- Introduced new test utilities for TUI interactions, for simulation of user input and navigation.
- Removed redundant code

- rename articles.go to parser.go to avoid redundancy

- Introduced an ArticleRepository in the repo package to manage articles.
- Created validation services for various data types including strings, URLs, emails, dates, and file paths.
- Implemented a Validator struct for fluent validation checks and error handling.

refactor: Refactored BookHandler methods and tests for improved clarity

- Consolidated book search and addition logic into SearchAndAddBook method.
- Revised tests
- Removed deprecated methods and streamlined test cases