The chart-renderer service accepts a JSON blob that it expects to follow a certain format, but it doesn't currently validate this. We should validate this input, perhaps using the express-validator NPM package.
Acceptance Criteria
- Requests made to the chart-renderer service are validated (using the schema definition from T372307)
- Requests that fail validation are logged
- The decision around which library we are using has been recorded in the codebase as a decision record. The decision record should capture why we choose Zod for validation as opposed to "just" TypeScript, and other libraries we considered and rejedcted.