Apply the finding engine to schematic and PCB reviews.

FACT, REQUIREMENT, and INFERENCE are separate fields; datasheet provenance
lives in the rule DB so Recommended cannot stay ERROR; LLM output is REVIEW.
Designer decisions persist across rescans. Schematic and PCB share one library
and the same finding object in the report UI.

backend/services/validation.py

@@ -21,6 +21,7 @@ from typing import Awaitable, Callable
 
 log = logging.getLogger(__name__)
 
+from backend.periscopex.finding_engine import apply_decisions
 from backend.periscopex.models import (
     ComponentConstraints,
     ComponentType,
@@ -789,6 +790,12 @@ async def validate_design_async(
     def _write_report(paused: bool = False) -> ValidationReport:
         annotate_findings_cad(all_findings, graph.cad_index)
         assign_finding_ids(all_findings)
+        dec_path = existing_path.with_name("decisions.json")
+        if dec_path.is_file():
+            try:
+                apply_decisions(all_findings, json.loads(dec_path.read_text()))
+            except Exception:
+                log.exception("decisions.json apply failed")
         summary = {"total": len(all_findings), "ERROR": 0, "WARNING": 0, "INFO": 0}
         for f in all_findings:
             summary[f.status] = summary.get(f.status, 0) + 1