test(web): refresh system-prompt pins for the web_search summary field

Three Web snapshots pinned on master after this branch's original base still
listed the web_search source type without the optional summary member.

snapshots/web/official-subagent-bundle/system-prompt.expected.md

@@ -926,6 +926,7 @@ interface ToolOutputMap {
       url: string;
       title?: string;
       snippet?: string;
+      summary?: string;
       publishedAt?: string;
     }[];
     truncated: boolean;

snapshots/web/optional-string-editor/system-prompt.expected.md

@@ -931,6 +931,7 @@ interface ToolOutputMap {
       url: string;
       title?: string;
       snippet?: string;
+      summary?: string;
       publishedAt?: string;
     }[];
     truncated: boolean;

snapshots/web/ptc-round/system-prompt.expected.md

@@ -913,6 +913,7 @@ interface ToolOutputMap {
       url: string;
       title?: string;
       snippet?: string;
+      summary?: string;
       publishedAt?: string;
     }[];
     truncated: boolean;