#22263: fix: send button hidden by long node names or small screens

## Summary - Long node/session names in the connection pill would push the send (and stop) button off screen, preventing users from sending messages - Constrain the connection pill width so the session label truncates with ellipsis instead of overflowing - Maintain the send button at the trailing edge via `SpaceBetween` arrangement - Also affects small screen devices where horizontal space is limited ## Test plan - [ ] Set a long node name and verify the send button remains visible and tappable - [ ] Verify short node names still display fully with the button at the right edge - [ ] Test the stop button visibility during an active run with a long node name - [ ] Test on a small screen device/emulator 🤖 Generated with [Claude Code](https://claude.com/claude-code) <!-- greptile_comment --> <h3>Greptile Summary</h3> Fixed send button visibility issue by constraining the connection pill width and using `SpaceBetween` arrangement. Long node/session names now truncate with ellipsis instead of pushing the send button off-screen. - Replaced `Spacer` with `Arrangement.SpaceBetween` for proper button positioning - Added `weight(1f, fill = false)` to ConnectionPill to allow flexible sizing - Applied `maxLines = 1` with `TextOverflow.Ellipsis` to session label text for truncation <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The changes are focused, well-implemented, and follow Compose best practices. The solution correctly addresses the layout issue by using appropriate Compose modifiers (`weight` with `fill = false`, `TextOverflow.Ellipsis`) and layout arrangements (`SpaceBetween`). No logical errors, security concerns, or breaking changes introduced. - No files require special attention _{Last reviewed commit: 69b0726} <!-- greptile_other_comments_section --> _{(3/5) Reply to the agent's comments like "Can you suggest a fix for this @greptileai?" or ask follow-up questions!} <!-- /greptile_comment -->