Add --min and --max flags to filter by line count

[MatthewMckee4]

Summary

Add --min <N> and --max <N> flags that filter results to only show files within a given line count range. Useful for finding large files that may need refactoring or ignoring trivially small files.

Example

# Show only files with more than 100 lines
kount --min 100 .

# Show only files between 50 and 200 lines
kount --min 50 --max 200 .

Acceptance criteria

• --min <N> filters out files with fewer than N lines
• --max <N> filters out files with more than N lines
• Both can be used together
• Totals reflect only the filtered results