feat: Add Visual Block Mode Support and Blinking Feature

[ashkansamadiyan]

This PR adds two major features to visimatch.nvim and improves documentation:

Visual Block Mode Support

• Added full support for visual block mode (^V)
• Implemented proper highlighting for block selections
• Added configuration options for block mode appearance
• Set reasonable defaults for block mode behavior

Blinking Feature

• Added blinking functionality to indicate when matches are found
• Particularly useful for large files to provide visual feedback
• Configurable blink timing and highlight groups
• Smart blinking that only activates for character-wise and block selections

Documentation Updates

• Updated README with new features and configuration options
• Added clear explanations for new functionality
• Improved configuration documentation clarity
• Added new screenshot showcasing the features

Technical Details

• Added new configuration options:
  • blink_enabled: Toggle blinking feature
  • blink_time: Control blink interval
  • blink_hl_group: Customize blink appearance
  • block_hl_group: Style block mode matches
  • block_max_width: Control maximum block width
• Optimized performance for both features
• Maintained backward compatibility

Testing

• Tested with various file types and sizes
• Verified performance in large files
• Confirmed compatibility with existing features
• Tested all visual modes: v, V, and ^V

Screenshot added to README