Set a user agent suffix when used as a mcp server (#3395)

This automatically adds a user agent suffix whenever the CLI is used as
a MCP server

codex-rs/protocol-ts/Cargo.toml

@@ -16,6 +16,7 @@ path = "src/main.rs"
 
 [dependencies]
 anyhow = "1"
+mcp-types = { path = "../mcp-types" }
 codex-protocol = { path = "../protocol" }
 ts-rs = "11"
 clap = { version = "4", features = ["derive"] }