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/pcb_review.py

@@ -30,6 +30,11 @@ are in the context. Never assume 1 oz or 50 Ω.
 - Creepage/clearance only if the extraction or IEC number is in context.
 
 ### Findings
+This is a **design review** of geometry vs the library JSON, not a second \
+datasheet exam. Put board measurements in `finding` (FACT), library text in \
+`why` (REQUIREMENT). Recommended layout notes are never ERROR. Missing \
+width/thickness/I_load → say insufficient evidence, do not assume 1 oz.
+
 Every finding MUST have status ERROR, WARNING, or INFO and a non-empty \
 recommendation. Call submit_review. Empty findings with checked_areas is \
 valid when the layout matches the extraction.