Report runtime MCP connection status (#40068)

## Why

MCP inventory can be cached or collected separately from a thread's live
connections, so tool availability alone does not describe the current runtime
state.

## What changed

- Add a nullable `runtimeStatus` to `mcpServerStatus/list` for thread-scoped
  requests, covering not-started, starting, connected, authentication-required,
  failed, cancelled, and disabled connections.
- Observe published connection state without starting or reconnecting servers,
  and return an unknown status when no thread is supplied or the active
  configuration no longer matches the published registration.
- Show connection state and tool counts in the compact `/mcp` view while
  retaining the detailed inventory in `/mcp verbose` and compatibility with
  servers that omit `runtimeStatus`.

## Testing

- Cover runtime status transitions, deferred and disabled servers, closed
  transports, configuration changes, protocol compatibility, and TUI rendering.

GitOrigin-RevId: e3bb6efe652f0fa8b3c97d5c53e4729b3a87cd91

codex-rs/protocol/src/mcp.rs

@@ -9,6 +9,20 @@ use serde::Serialize;
 use std::collections::HashMap;
 use ts_rs::TS;
 
+/// Observed state of an MCP connection in a published thread runtime.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(rename_all = "camelCase")]
+pub enum McpServerConnectionStatus {
+    NotStarted,
+    Starting,
+    Connected,
+    AuthenticationRequired,
+    Failed,
+    Cancelled,
+    Disabled,
+}
+
 /// Extension ID for OpenAI form elicitation.
 pub const OPENAI_FORM_EXTENSION_ID: &str = "openai/form";
 /// Extension ID for standard MCP form elicitations that require user-entered input.