feat(reporting): add LLM-based vulnerability deduplication

- Add dedupe.py with XML-based LLM deduplication using direct litellm calls
- Integrate deduplication check in create_vulnerability_report tool
- Add get_existing_vulnerabilities() method to tracer for fetching reports
- Update schema and system prompt with deduplication guidelines

strix/telemetry/tracer.py

@@ -145,6 +145,9 @@ class Tracer:
         self.save_run_data()
         return report_id
 
+    def get_existing_vulnerabilities(self) -> list[dict[str, Any]]:
+        return list(self.vulnerability_reports)
+
     def update_scan_final_fields(
         self,
         executive_summary: str,