feat: add support for mistral model

examples/mistral.ts

packages/core/package.json

packages/core/src/index.ts

packages/core/src/llm/index.ts

packages/core/src/llm/mistral.ts

packages/core/tsconfig.json

packages/core/types/mistral.d.ts

packages/eslint-config-custom/index.js

pnpm-lock.yaml