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The `codex-protocol-ts` crate that `codex generate-ts` uses is out of
date now since it doesn't handle the V2 namespace from: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/Cargo.lock

@@ -979,7 +979,6 @@ dependencies = [
  "codex-mcp-server",
  "codex-process-hardening",
  "codex-protocol",
- "codex-protocol-ts",
  "codex-responses-api-proxy",
  "codex-rmcp-client",
  "codex-stdio-to-uds",
@@ -1363,16 +1362,6 @@ dependencies = [
  "uuid",
 ]
 
-[[package]]
-name = "codex-protocol-ts"
-version = "0.0.0"
-dependencies = [
- "anyhow",
- "clap",
- "codex-app-server-protocol",
- "ts-rs",
-]
-
 [[package]]
 name = "codex-responses-api-proxy"
 version = "0.0.0"