Ajv — consistent, modern (v8) idioms

Ajv 8 made three moves that training data hasn't absorbed: dialects split across entry points (default = draft-07; 2020-12 lives at ajv/dist/2020), formats moved out to ajv-formats, and strict mode by default. Generated code therefore validates against the wrong draft, silently skips format checks, recompiles per request, and reads overwritten validate.errors. This skill pins the canonical Ajv 8 setup.

Canonical idioms — always X, never Y