Add MODE=pcb layout exam job with AI and deterministic checks.

Parallel pcb_status pipeline: parse board, classify domains/groups,
inventory traces, PE-LAY/PLC/SI/DRT checks, per-IC datasheet review.
Findings merge into the report UI. No auto-place or pcbnew write-back.

backend/services/pipeline.py

@@ -264,6 +264,8 @@ class PipelineWorkspace:
             self._upload_file("bom_summary.json")
             self._upload_file("derating.json")
             self._upload_file("report.json")
+            self._upload_file("pcb_report.json")
+            self._upload_file("pcb_inventory.json")
             self._upload_file("periscope-findings.json")
             self._upload_file("review_fingerprints.json")
             self._upload_file("api_logs.jsonl")