Replace Guardian tickets with parent response IDs (#43002)

## What changed

Capture the ID from `response.created` and pass it as `parent_response_id` in Guardian review and classifier request metadata. Clear the current response ID before sampling retries so tool reviews cannot inherit a failed response's ID.

Request Guardian credits with `guardian_credits_requested` on eligible parent requests. Remove the ticket protocol, transport attachment, and ticket-specific body redaction. Keep ordinary app-server client `parent_response_id` values inside `x-codex-turn-metadata` rather than promoting them to Guardian request metadata.

## Testing

Update coverage for HTTP fallback, WebSocket review reuse, missing response IDs, classifier transport retries, and code-mode yield/resume attribution. Extend app-server tests to verify client metadata placement over HTTP and WebSocket.

GitOrigin-RevId: c1665e56382ecec8d260fc2ca0ecd5e20b0b2391

codex-rs/codex-api/src/common.rs

@@ -94,11 +94,15 @@ pub struct MemorySummarizeOutput {
     pub memory_summary: String,
 }
 
+/// The server response currently being handled, shared with tool-review extensions.
+#[derive(Clone, Debug)]
+pub struct ResponseId(pub String);
+
 #[derive(Debug)]
 pub enum ResponseEvent {
     Created {
-        /// Runtime-only receipt for this exact server response.
-        guardian_ticket: Option<codex_protocol::guardian_ticket::GuardianTicket>,
+        /// Existing server response ID, when supplied by the stream.
+        response_id: Option<String>,
     },
     SafetyBuffering(SafetyBuffering),
     OutputItemDone(ResponseItem),