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/periscopex/models.py

@@ -356,6 +356,19 @@ class Finding(BaseModel):
     cad_sheet: str | None = None     # schematic sheet filename for plugin sync
     cad_uuid: str | None = None      # KiCad symbol/pin uuid
     variant: str | None = None      # DNP / ECO / assembly variant
+    # Finding engine (docs/motore-finding.md) — optional for legacy JSON.
+    facts: str = ""
+    requirement: str = ""
+    inference: str = ""
+    provenance: Literal["MANDATORY", "RECOMMENDED", "TYPICAL", "EXAMPLE"] | None = None
+    finding_class: Literal["RULE", "RISK", "REVIEW", "INFO"] | None = None
+    confidence: float | None = None
+    evidence_status: Literal["SUFFICIENT", "INSUFFICIENT"] | None = None
+    calculation: str = ""
+    assumptions: list[str] = []
+    action: str = ""
+    decision_id: str | None = None
+    suppressed: bool = False
 
 
 class ValidationReport(BaseModel):