feat: add threadId to MCP server messages (#9192)

This favors `threadId` instead of `conversationId` so we use the same
terms as https://developers.openai.com/codex/sdk/.

To test the local build:

```
cd codex-rs
cargo build --bin codex
npx -y @modelcontextprotocol/inspector ./target/debug/codex mcp-server
```

I sent:

```json
{
  "method": "tools/call",
  "params": {
    "name": "codex",
    "arguments": {
      "prompt": "favorite ls option?"
    },
    "_meta": {
      "progressToken": 0
    }
  }
}
```

and got:

```json
{
  "content": [
    {
      "type": "text",
      "text": "`ls -lah` (or `ls -alh`) — long listing, includes dotfiles, human-readable sizes."
    }
  ],
  "structuredContent": {
    "threadId": "019bbb20-bff6-7130-83aa-bf45ab33250e"
  }
}
```

and successfully used the `threadId` in the follow-up with the
`codex-reply` tool call:

```json
{
  "method": "tools/call",
  "params": {
    "name": "codex-reply",
    "arguments": {
      "prompt": "what is the long versoin",
      "threadId": "019bbb20-bff6-7130-83aa-bf45ab33250e"
    },
    "_meta": {
      "progressToken": 1
    }
  }
}
```

whose response also has the `threadId`:

```json
{
  "content": [
    {
      "type": "text",
      "text": "Long listing is `ls -l` (adds permissions, owner/group, size, timestamp)."
    }
  ],
  "structuredContent": {
    "threadId": "019bbb20-bff6-7130-83aa-bf45ab33250e"
  }
}
```

Fixes https://github.com/openai/codex/issues/3712.

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

@@ -6,6 +6,7 @@ use codex_core::CodexThread;
 use codex_core::protocol::FileChange;
 use codex_core::protocol::Op;
 use codex_core::protocol::ReviewDecision;
+use codex_protocol::ThreadId;
 use mcp_types::ElicitRequest;
 use mcp_types::ElicitRequestParamsRequestedSchema;
 use mcp_types::JSONRPCErrorError;
@@ -19,11 +20,13 @@ use tracing::error;
 use crate::codex_tool_runner::INVALID_PARAMS_ERROR_CODE;
 use crate::outgoing_message::OutgoingMessageSender;
 
-#[derive(Debug, Serialize)]
+#[derive(Debug, Deserialize, Serialize)]
 pub struct PatchApprovalElicitRequestParams {
     pub message: String,
     #[serde(rename = "requestedSchema")]
     pub requested_schema: ElicitRequestParamsRequestedSchema,
+    #[serde(rename = "threadId")]
+    pub thread_id: ThreadId,
     pub codex_elicitation: String,
     pub codex_mcp_tool_call_id: String,
     pub codex_event_id: String,
@@ -51,6 +54,7 @@ pub(crate) async fn handle_patch_approval_request(
     request_id: RequestId,
     tool_call_id: String,
     event_id: String,
+    thread_id: ThreadId,
 ) {
     let mut message_lines = Vec::new();
     if let Some(r) = &reason {
@@ -65,6 +69,7 @@ pub(crate) async fn handle_patch_approval_request(
             properties: json!({}),
             required: None,
         },
+        thread_id,
         codex_elicitation: "patch-approval".to_string(),
         codex_mcp_tool_call_id: tool_call_id.clone(),
         codex_event_id: event_id.clone(),