feat(web-search): tool DuckDuckGo abierta en /web-search para watsonx Orchestrate

Sub-app FastAPI montada en /web-search con búsqueda vía ddgs.
OpenAPI 3.0.3 + servers absoluto + operationId webSearch listo para
importar como external tool en wxO. Sin auth (uso de taller/demo).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/web_search/search.py

@@ -0,0 +1,65 @@
+"""Único punto del servicio que toca ddgs.
+
+Si se cambia el backend (Brave, Google CSE, etc.) sólo se reescribe este módulo;
+el contrato `search_web(...)` -> list[SearchResult] no cambia.
+"""
+from __future__ import annotations
+
+import html
+import re
+from dataclasses import dataclass
+
+from ddgs import DDGS
+
+
+SNIPPET_MAX_LEN = 300
+_TAG_RE = re.compile(r"<[^>]+>")
+_WS_RE = re.compile(r"\s+")
+
+
+class SearchProviderError(RuntimeError):
+    """Error opaco del proveedor de búsqueda. main.py lo traduce a HTTP 502."""
+
+
+@dataclass(frozen=True)
+class SearchResult:
+    title: str
+    url: str
+    snippet: str
+
+
+def _clean_snippet(raw: str | None) -> str:
+    if not raw:
+        return ""
+    text = _TAG_RE.sub("", raw)
+    text = html.unescape(text)
+    text = _WS_RE.sub(" ", text).strip()
+    if len(text) > SNIPPET_MAX_LEN:
+        text = text[: SNIPPET_MAX_LEN - 1].rstrip() + "…"
+    return text
+
+
+def search_web(query: str, max_results: int, region: str, timeout: int) -> list[SearchResult]:
+    try:
+        raw = DDGS(timeout=timeout).text(
+            query,
+            region=region,
+            max_results=max_results,
+        )
+    except Exception as exc:  # ddgs lanza varias excepciones distintas; las unificamos
+        raise SearchProviderError(str(exc)) from exc
+
+    results: list[SearchResult] = []
+    for item in raw or []:
+        title = (item.get("title") or "").strip()
+        url = (item.get("href") or item.get("url") or "").strip()
+        if not url:
+            continue
+        results.append(
+            SearchResult(
+                title=title or url,
+                url=url,
+                snippet=_clean_snippet(item.get("body") or item.get("snippet")),
+            )
+        )
+    return results