fix(cas): responsive schema form grid, widen launch inputs page

[scottcmg]

What

Makes the agent schema form lay out responsively at any width.

• Grid: switched from a fixed container-query breakpoint to an intrinsic auto-fit grid (minmax(min(100%, 15rem), 1fr)). Fields now pair into two columns when there's room and collapse to one when tight — at every nesting level, since each grid sizes to its own width rather than inheriting the outer form's. Added min-width: 0 on grid cells so long labels/inputs shrink instead of overflowing into their neighbor, and full-row spanning for object/array fields.
• Launch page: widened the inputs container (w-[55%] max-w-[600px]) so the two-column layout actually has room on the launch screen.

Why

Noticed while filming the bug-bash demo — unrelated to the bug-bash fixes, so raising it separately. Previously the columns could overlap/clip at narrow widths and nested object grids stayed stuck at two cramped columns.

Demo

Screen.Recording.2026-07-01.at.5.23.25.PM.mov

Testing

Verified in the standalone chat across window widths: two columns when wide, single column when narrow, nested objects collapse independently, no overlap.

🤖 Generated with Claude Code

[github-actions]

📊 Coverage Report

Package	Line Coverage
datatable	88.29%
multi-file-upload	87.27%
conversational-agent-chat	89.09%
validation-station	97.97%

[maxduu]

Thanks!