Ensure Data Quality and Validation

Integrate automated data quality checks and validation processes to ensure that data from diverse sources is clean, accurate, and reliable before being used for analytics.

Stories:
- [ ] #75
- [ ] #76
- [ ] #77

Start by reading the three story references, #75, #76, and #77, because this issue does not identify files, tests, tools, or an implementation entry point. Use those stories to determine the required data-quality checks and validation scope; done means data from diverse sources is clean, accurate, and reliable before analytics use.

Written by the indexing model from the issue text.