Rosetta autonomous onboarding

One call to `POST /api/rosetta/ingest` takes a merchant payload, proposes a canonical mapping, validates it against the catalog schemas, and stages the result for review.

Rosetta is our translation layer between merchant payloads and our canonical schemas (offer, product, observation, match, action). The new ingest endpoint runs the full proposal-to-staged-mapping pipeline in a single call, so a merchant or an agent can onboard without clicking through the Mapping Studio.

New `POST /api/rosetta/ingest` endpoint backed by the `lastprice/rosetta-ingest` builtin

Rosetta dashboard now has six tabs: Translate, Mapping Studio, Onboard, Canonical Schemas, Review Queue, Frozen Adapters

Mapping Studio supports both UI editors and agent-driven JSON edits

Built-in catalog now includes Rosetta's six functions (translate, normalize, validate, suggest, freeze, ingest) for a total of 15 built-ins across Jale, Elo, and Rosetta