Expose structured standalone web search results (#32898)

## Why

Standalone web search can return structured result DTOs separately from its
model-facing text output. App-server clients need access to that data without
coupling Codex to every result type or field.

## What changed

- Preserve the optional `results` array from `/v1/alpha/search` as opaque JSON
  through web-search completion events, thread history, and app-server
  `webSearch` items.
- Keep responses from older endpoints compatible when `results` is absent, and
  allow clients to ignore result types and fields they do not understand.
- Regenerate the protocol schemas and TypeScript definitions for the optional
  field.

## Testing

- Cover responses with missing, empty, and forward-compatible result payloads.
- Verify standalone web-search results round-trip through app-server item
  notifications and thread-item conversion.

GitOrigin-RevId: 739ef5694ece5733f7b8749ec41d6bfa3f33c8c5

codex-rs/core/src/event_mapping.rs

@@ -206,6 +206,7 @@ pub fn parse_turn_item(item: &ResponseItem) -> Option<TurnItem> {
                 id: id.as_deref().unwrap_or_default().to_string(),
                 query,
                 action,
+                results: None,
             }))
         }
         ResponseItem::ImageGenerationCall {

codex-rs/core/src/event_mapping_tests.rs

@@ -509,6 +509,7 @@ fn parses_web_search_call() {
                     query: Some("weather".to_string()),
                     queries: None,
                 },
+                results: None,
             }
         ),
         other => panic!("expected TurnItem::WebSearch, got {other:?}"),
@@ -537,6 +538,7 @@ fn parses_web_search_open_page_call() {
                 action: WebSearchAction::OpenPage {
                     url: Some("https://example.com".to_string()),
                 },
+                results: None,
             }
         ),
         other => panic!("expected TurnItem::WebSearch, got {other:?}"),
@@ -567,6 +569,7 @@ fn parses_web_search_find_in_page_call() {
                     url: Some("https://example.com".to_string()),
                     pattern: Some("needle".to_string()),
                 },
+                results: None,
             }
         ),
         other => panic!("expected TurnItem::WebSearch, got {other:?}"),
@@ -590,6 +593,7 @@ fn parses_partial_web_search_call_without_action_as_other() {
                 id: "ws_partial".to_string(),
                 query: String::new(),
                 action: WebSearchAction::Other,
+                results: None,
             }
         ),
         other => panic!("expected TurnItem::WebSearch, got {other:?}"),

codex-rs/core/src/tools/handlers/extension_tools.rs

@@ -272,6 +272,7 @@ mod tests {
                         id: call.call_id.clone(),
                         query: String::new(),
                         action: None,
+                        results: None,
                     }),
                     legacy_events: Vec::new(),
                 })
@@ -421,6 +422,7 @@ mod tests {
                 id: "call-extension".to_string(),
                 query: String::new(),
                 action: None,
+                results: None,
             }
         );
     }