Add single-server MCP status discovery with thread connection reuse (#48783)

## Why

Inspecting one MCP server should not require full-inventory discovery or a separate connection when a thread already has one.

## What changed

- Add optional `serverName` to `mcpServerStatus/list` and update generated schemas and bindings.
- With `threadId`, apply any pending runtime refresh and reuse the thread's current connection and tool catalog, waiting only for the selected server during discovery.
- Without `threadId`, create a discovery connection for only the selected server. Unknown names return an empty page; omitting `serverName` preserves full-inventory discovery.

## Testing

Add a regression test covering both status detail modes, checking that tool metadata is preserved and that status reads do not repeat `initialize` or `tools/list` requests.

GitOrigin-RevId: 1b361b67a993ab45cae493e88c146f50cfaf753a

codex-rs/app-server-protocol/schema/json/ClientRequest.json

@@ -1733,6 +1733,13 @@
             "null"
           ]
         },
+        "serverName": {
+          "description": "Limit discovery to one server. With a thread ID, reuse that thread's MCP connection.",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
         "threadId": {
           "type": [
             "string",