feat(research): enable adaptive librarian retrieval

[GTC2333]

Summary

• give Librarian bounded Bash/Edit access for direct public retrieval fallbacks
• give literature-scout and api-librarian the same bounded shell capability while keeping evidence-extractor shell-free
• integrate MCP-first retrieval, timeout/size bounds, untrusted-content handling, and exact evidence provenance into the existing English prompts

Validation

• Runtime build: passed
• Runtime typecheck: passed
• Full test suite: 106 files, 1122 tests passed
• Repository build: pre-existing Web TypeScript errors on origin/dev; this PR changes Runtime files only