fix: устойчивый парсинг LLM-ответа — обработка markdown code blocks

- llm.py:  возвращён (нужен для structured output)
- Добавлен fallback-парсинг для ответов обёрнутых в ```json
- Устранён undefined-variable баг в except-блоке

guarddog_nexus/llm.py

@@ -83,9 +83,24 @@ async def analyze_finding(finding_data: dict) -> dict | None:
         content = body["choices"][0]["message"]["content"]
         return json.loads(content)
     except (KeyError, IndexError, json.JSONDecodeError) as e:
+        raw = ""
+        try:
+            raw = body["choices"][0]["message"]["content"]
+        except (KeyError, IndexError):
+            raw = str(body)[:300]
+        # Some models wrap JSON in markdown code blocks
+        if isinstance(raw, str) and raw.strip().startswith("```"):
+            try:
+                stripped = raw.strip().strip("`").strip()
+                if stripped.startswith("json\n"):
+                    stripped = stripped[5:]
+                return json.loads(stripped)
+            except json.JSONDecodeError:
+                pass
         log.warning(
-            "LLM response parse error for rule=%s: %s",
+            "LLM response parse error for rule=%s: %s — raw=%s",
             finding_data.get("rule"),
             e,
+            raw[:200] if isinstance(raw, str) else str(raw)[:200],
         )
         return None