fix: use generate_ts from app_server_protocol (#6407)

Update `codex generate-ts` to use the TS export code from
`app-server-protocol/src/export.rs`.

I realized there were two duplicate implementations of Typescript export
code:
- `app-server-protocol/src/export.rs`
- the `codex-protocol-ts` crate

The `codex-protocol-ts` crate that `codex generate-ts` uses is out of
date now since it doesn't handle the V2 namespace from:
https://github.com/openai/codex/pull/6212.

codex-rs/cli/Cargo.toml

@@ -30,7 +30,6 @@ codex-login = { workspace = true }
 codex-mcp-server = { workspace = true }
 codex-process-hardening = { workspace = true }
 codex-protocol = { workspace = true }
-codex-protocol-ts = { workspace = true }
 codex-responses-api-proxy = { workspace = true }
 codex-rmcp-client = { workspace = true }
 codex-stdio-to-uds = { workspace = true }