Code execution discloses 90s limit; web tools drop consumed blocks

Code execution tool now supports code_execution_20260521, which discloses the 90-second per-cell execution time limit in the tool description. Web search and web fetch tools now support web_search_20260318 and web_fetch_20260318, adding a response_inclusion parameter to drop consumed result blocks from the API response for agentic workflows. No beta header required for either.