Native DeepSeek datasheet extraction in periscope/src (Fase C3).

Pipeline and LCSC resolve call datasheet_extract; inherited extraction.py
stays in dependency as fallback. No Anthropic Console skill ids.

tests/test_pdf_ingest.py

@@ -4,7 +4,7 @@ from __future__ import annotations
 
 from pathlib import Path
 
-from backend.services.extraction import _coerce_abs_max
+from backend.services.datasheet_extract import _coerce_abs_max
 from backend.services.llm.pdf_ingest import (
     extract_pdf_text,
     make_text_pdf,