Speed up /mcp inventory listing (#16831)

Addresses #16244

This was a performance regression introduced when we moved the TUI on
top of the app server API.

Problem: `/mcp` rebuilt a full MCP inventory through
`mcpServerStatus/list`, including resources and resource templates that
made the TUI wait on slow inventory probes.

Solution: add a lightweight `detail` mode to `mcpServerStatus/list`,
have `/mcp` request tools-and-auth only, and cover the fast path with
app-server and TUI tests.

Testing: Confirmed slow (multi-second) response prior to change and
immediate response after change.

I considered two options:
1. Change the existing `mcpServerStatus/list` API to accept an optional
"details" parameter so callers can request only a subset of the
information.
2. Add a separate `mcpServer/list` API that returns only the servers,
tools, and auth but omits the resources.

I chose option 1, but option 2 is also a reasonable approach.

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

@@ -1042,6 +1042,17 @@
             "null"
           ]
         },
+        "detail": {
+          "anyOf": [
+            {
+              "$ref": "#/definitions/McpServerStatusDetail"
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "description": "Controls how much MCP inventory data to fetch for each server. Defaults to `Full` when omitted."
+        },
         "limit": {
           "description": "Optional page size; defaults to a server-defined value.",
           "format": "uint32",
@@ -1235,6 +1246,13 @@
       ],
       "type": "object"
     },
+    "McpServerStatusDetail": {
+      "enum": [
+        "full",
+        "toolsAndAuthOnly"
+      ],
+      "type": "string"
+    },
     "MergeStrategy": {
       "enum": [
         "replace",