## What changed
- Advertise `openai/elicitation` form support when the client declares an
object-valued `form` capability, without deriving it from the legacy
`openai/form` capability.
- Handle `openai/elicitation/create` requests in `form` mode and forward their
metadata and opaque schema through app-server as `openaiForm`, preserving
`x-openai-*` annotations.
- Keep legacy form handling independent and have the TUI automatically decline
the new form requests it cannot render.
## Testing
- Add an app-server round-trip test for capability negotiation, request
forwarding, and accepted responses.
- Extend MCP capability filtering coverage for `openai/elicitation.form`.
GitOrigin-RevId: 88f39257bffafe4ee98a9c910e38507843cd7eeb