Add Markdown Formatting Support

[xectrone]

Description:
Currently, QuickMark allows users to take notes in markdown files, but it lacks built-in support for markdown formatting. Adding markdown formatting support will enhance the app's functionality by enabling users to format their notes directly within the app, making their notes more readable and organized.

Proposed Solution:
Introduce markdown formatting support within the note editor, allowing users to easily apply common markdown elements such as headings, bold, italics, lists, links, and code blocks.

Implementation Details:

1. UI Changes:

   • Add a formatting toolbar above the note editor with buttons for common markdown elements (headings, bold, italics, lists, links, code blocks).

2. Functionality:

   • Implement functions to insert markdown syntax at the cursor position when a formatting button is clicked.
   • Ensure that the markdown syntax is correctly applied and can be toggled on and off.
   • Provide real-time syntax highlighting within the editor for better readability.

3. Preview Mode:

   • Implement a markdown preview mode to render the formatted text as it would appear in a markdown viewer.
   • Allow users to toggle between the raw markdown text and the rendered preview.

Feel free to add any additional information or modify the details as needed. Thank you for considering this feature request!