Chat Input Overflows on Narrow Sidebar

Priority: P2 Issue: #6273

Remaining Work

• Make the chat input toolbar responsive: wrap controls to a second row when sidebar is narrow
• Send button should always remain visible and anchored to the bottom-right
• Use CSS flexbox flex-wrap: wrap or container queries / ResizeObserver
• Test at sidebar widths of ~200px, ~280px, and ~350px