Extends ingest_one_code_asset's allowlist + 4-arm match (parser_version /
chunker_version / extract / chunks) to admit code_lang "shell" and route it
to CodeTextParagraphV1Chunker. parser_version "none-v1" + synthesize_tier2_document
reused.
Tier 1/2 fallback wrapper lands in the next commit.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>