add support for versioned recipes, more robust dataframing

[matthewpeterkort]

Loom Explorer Builder stack

This is the foundation of a six-PR review stack. Merge strictly in order:

1. add support for versioned recipes, more robust dataframing #17 — Versioned recipes and robust dataframing ← this PR
2. add Explorer recipe lifecycle and publication orchestration #18 — Explorer recipe lifecycle and publication orchestration
3. expose project graph data and harden builder resolution #19 — Project graph data and builder resolution
4. add semantic concept contracts, catalog correlation, and rules #20 — Semantic concept contracts, catalog correlation, and rules
5. expose the authenticated semantic concept catalog #21 — Authenticated semantic concept catalog API
6. lower semantic concept selections into dataframe recipes #22 — Semantic concept selections integrated into recipes

Next: #18

Summary

Adds versioned recipe storage and resolution, strengthens dataframe compilation and publication, expands recipe execution APIs, and establishes the backend foundation required by the Explorer builder stack.

Review and merge procedure

Review each PR against its immediate base branch. Merge #17 first, then #18 through #22 in numerical order. After each merge, retarget the next PR to main if GitHub does not do so automatically.

Validation

Loom CI passes for this branch. Each later stack layer has its own CI run and image build.