Previously, bash tool overflow errors gave generic messages that didn't
help agents understand what went wrong or how much data was processed.

Changes:
- Track specific overflow reason (line too long, total bytes exceeded, or max lines exceeded)
- Include actual values in error messages (bytes read, line count, etc.)
- Show which limit was violated with comparison (e.g., '17000 bytes > 16384 bytes')
- Update overflow message format to include specific reason upfront
- Improve fallback error when temp file creation fails

Example new messages:
- 'Line 50 exceeded per-line limit: 2048 bytes > 1024 bytes'
- 'Total output exceeded limit: 17000 bytes > 16384 bytes (at line 200)'
- 'Line count exceeded limit: 300 lines >= 300 lines (15000 bytes read)'

This gives agents actionable information to adjust their commands
(e.g., add grep filters, use head/tail with correct line counts).

_Generated with `cmux`_