fix(web): pass proxy to DDGS client

The DuckDuckGo search provider instantiated DDGS(timeout=10) without
passing the configured proxy, making web_search unusable in environments
that require a proxy (e.g. behind GFW). DDGS supports a proxy parameter
and the proxy value is already available as self.proxy — it was simply
not forwarded.

Add a test verifying the proxy kwarg is forwarded to DDGS.

nanobot/agent/tools/web.py

@@ -759,7 +759,7 @@ class WebSearchTool(Tool):
             # We run it in a thread to avoid blocking the loop
             from ddgs import DDGS
 
-            ddgs = DDGS(timeout=10)
+            ddgs = DDGS(timeout=10, proxy=self.proxy)
             raw = await asyncio.wait_for(
                 asyncio.to_thread(ddgs.text, query, max_results=n),
                 timeout=self.config.timeout,