Closes #2102

Summary

Adds a warning to the response when Google search API caps results at 10.

Changes

• Added warning field to result when num_results > 10
• Warning message: "Google API limited results to 10 (requested {num_results})"

Why?

Google Custom Search API has a hard limit of 10 results per request. Previously, requests for more results were silently capped without informing the user.

Example

result = web_search(query="test", num_results=15, provider="google")
# Returns: {
#   "query": "test",
#   "results": [...],  # 10 items
#   "total": 10,
#   "provider": "google",
#   "warning": "Google API limited results to 10 (requested 15)"
# }

Testing

✅ Requests ≤10: No warning
✅ Requests >10: Warning added to response