[app-server] centralize client response analytics (#20059)

## Why

The precursor PR keeps successful client responses typed until
app-server's outgoing response seam. This follow-up uses that seam to
move successful client-response analytics out of individual handlers and
into the shared sender path, while keeping filtering decisions inside
`codex-analytics`.

## What changed

- Emit successful client-response analytics centrally from
`OutgoingMessageSender::send_response`.
- Remove duplicate handler-local response tracking for the current
thread/turn lifecycle responses.
- Keep analytics ingestion selective inside `AnalyticsEventsClient`, so
unrelated client traffic is ignored before cloning or boxing.
- Collapse client-response analytics facts onto one typed path and
normalize payloads in the reducer.
- Add direct client-filter coverage plus sender-level coverage for the
centralized forwarding path.

## Verification

- `cargo test -p codex-analytics`
- `cargo test -p codex-app-server outgoing_message::tests --lib`

codex-rs/app-server/src/codex_message_processor.rs

@@ -42,7 +42,6 @@ use codex_app_server_protocol::CancelLoginAccountParams;
 use codex_app_server_protocol::CancelLoginAccountResponse;
 use codex_app_server_protocol::CancelLoginAccountStatus;
 use codex_app_server_protocol::ClientRequest;
-use codex_app_server_protocol::ClientResponse;
 use codex_app_server_protocol::ClientResponsePayload;
 use codex_app_server_protocol::CodexErrorInfo;
 use codex_app_server_protocol::CollaborationModeListParams;
@@ -2856,15 +2855,6 @@ impl CodexMessageProcessor {
 
         match result {
             Ok((response, notif)) => {
-                listener_task_context
-                    .analytics_events_client
-                    .track_response(
-                        request_id.connection_id.0,
-                        ClientResponse::ThreadStart {
-                            request_id: request_id.request_id.clone(),
-                            response: response.clone(),
-                        },
-                    );
                 listener_task_context
                     .outgoing
                     .send_response(request_id, response)
@@ -4402,13 +4392,6 @@ impl CodexMessageProcessor {
                     reasoning_effort: session_configured.reasoning_effort,
                 };
 
-                self.analytics_events_client.track_response(
-                    request_id.connection_id.0,
-                    ClientResponse::ThreadResume {
-                        request_id: request_id.request_id.clone(),
-                        response: response.clone(),
-                    },
-                );
                 let connection_id = request_id.connection_id;
                 let token_usage_thread = include_turns.then(|| response.thread.clone());
                 self.outgoing.send_response(request_id, response).await;
@@ -5020,13 +5003,6 @@ impl CodexMessageProcessor {
                 return;
             }
         };
-        self.analytics_events_client.track_response(
-            request_id.connection_id.0,
-            ClientResponse::ThreadFork {
-                request_id: request_id.request_id.clone(),
-                response: response.clone(),
-            },
-        );
         let connection_id = request_id.connection_id;
         let token_usage_thread = include_turns.then(|| response.thread.clone());
         self.outgoing.send_response(request_id, response).await;
@@ -6644,13 +6620,6 @@ impl CodexMessageProcessor {
 
         match result {
             Ok(response) => {
-                self.analytics_events_client.track_response(
-                    request_id.connection_id.0,
-                    ClientResponse::TurnStart {
-                        request_id: request_id.request_id.clone(),
-                        response: response.clone(),
-                    },
-                );
                 self.outgoing.send_response(request_id, response).await;
             }
             Err(error) => {
@@ -6821,13 +6790,6 @@ impl CodexMessageProcessor {
 
         match result {
             Ok(response) => {
-                self.analytics_events_client.track_response(
-                    request_id.connection_id.0,
-                    ClientResponse::TurnSteer {
-                        request_id: request_id.request_id.clone(),
-                        response: response.clone(),
-                    },
-                );
                 self.outgoing.send_response(request_id, response).await;
             }
             Err(error) => {