Support openai/form extended form elicitations (#27500)

# Summary
Allow App Server clients to opt into `openai/form` MCP elicitations.

codex-rs/memories/write/src/runtime.rs

@@ -313,6 +313,7 @@ impl MemoryStartupContext {
                 parent_trace: None,
                 environments,
                 thread_extension_init: Default::default(),
+                supports_openai_form_elicitation: false,
             })
             .await?;