#10707: fix(ui): prevent agents-main stretching to match sidebar height

## Summary - `.agents-main` in CSS grid stretches to match sidebar height when many agents (25+) are configured, making tab pills render as unusable vertical bars - Add `align-self: start` to `.agents-main` (the sibling `.agents-sidebar` already has it) ## Test plan - [x] Configure 20+ agents and verify tab pills render horizontally - [x] Single-agent layout unaffected Closes #10537 Generated with [Claude Code](https://claude.com/claude-code) <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> - Adjusts the Agents settings layout CSS so the main panel (`.agents-main`) doesn’t stretch to match the sidebar height when the sidebar becomes very tall. - Adds `align-self: start` to `.agents-main`, matching the existing `.agents-sidebar` behavior. - Intended to preserve horizontal “tab pill” rendering when many agents are configured by preventing excessive vertical stretching. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - Change is a single, targeted CSS tweak (`align-self: start`) scoped to `.agents-main` and aligns behavior with the sibling `.agents-sidebar`. No logic/code-path changes, and it directly addresses the described grid stretching issue. - No files require special attention <!-- greptile_other_comments_section --> <!-- /greptile_comment -->