Raise the MCP server recursion limit (#35414)

## What changed

- Set the Rust recursion limit to 256 for both the MCP server library and binary crates.
- Populate `started_at_ms` in the thread-fork test's completed-item fixture.

GitOrigin-RevId: b25eeaeecaf94265fe3be8f23cb3c395595afc2a

codex-rs/app-server/tests/suite/v2/thread_fork.rs

@@ -1395,6 +1395,7 @@ async fn assert_thread_fork_freezes_active_paginated_turn_as_interrupted(
                     text_elements: Vec::new(),
                 }],
             }),
+            started_at_ms: Some(0),
             completed_at_ms,
         }))
     };

codex-rs/mcp-server/src/lib.rs

@@ -1,4 +1,5 @@
 //! Prototype MCP server.
+#![recursion_limit = "256"]
 #![deny(clippy::print_stdout, clippy::print_stderr)]
 
 use std::io::ErrorKind;

codex-rs/mcp-server/src/main.rs

@@ -1,3 +1,5 @@
+#![recursion_limit = "256"]
+
 use codex_arg0::Arg0DispatchPaths;
 use codex_arg0::arg0_dispatch_or_else;
 use codex_mcp_server::run_main;