Migrate from DDG-specific search to the new generic WebSearchTools

We replaced the DuckDuckGo-specific web search tool with a generic WebSearchTools interface. This standardization broadens provider choice and future-proofs search integrations.

Details:

• Update any DDG-specific references to the new WebSearchTools
• Switch providers without redesigning your agents in the future

Who this is for: Teams embedding web search into agents who want provider flexibility and a stable interface.