ls plain text output columns misalign for long filenames or owner names

[github-actions]

Description

In tools/ls/ls.go, writePlain uses hardcoded format widths (%-10s, %8s). For entries with long owner names, long filenames, or large file sizes, columns fall out of alignment.

Steps to Reproduce

1. Create a directory with files owned by a user with a long username
2. Run aict ls . --plain
3. Observe misaligned columns

Expected Behavior

Column widths should be computed dynamically based on the longest value per column, matching GNU ls -l behavior.

Implementation Approach

1. First pass: collect all entries and compute maxOwnerLen, maxGroupLen, maxSizeLen
2. Second pass: format output using computed widths

Actual Behavior

Fixed-width columns cause visual misalignment when any value exceeds the hardcoded width.

Related

tools/ls/ls.go writePlain function