Fixes checkbox toggle failing with "Checkbox not found in file" error when task list items contain inline markdown formatting like bold, code, or strikethrough.

Problem

When toggling a checkbox in interactive mode, the parser strips inline markdown formatting from the displayed text, but the toggle function compares this stripped text against the raw file line which still contains formatting markers. This causes the match to fail.

Example that fails before this fix:

- [ ] **Bold task** - description
- [ ] `Code task` - description
- [ ] ~~Strikethrough~~ - description

Solution

Added strip_inline_markdown() helper function that removes common inline formatting markers (**, __, `, ~~) from the raw file line text before comparing it to the parsed text.

Testing

Tested with markdown files containing:

• **bold** text in checkboxes
• __bold__ alternative syntax
• `code` spans in checkboxes
• ~~strikethrough~~ text
• Multiple formatting in same line
• Regular checkboxes (no regression)