QRISK3 Instance 1 UK Biobank Pipeline

Initial stable release of the reproducible QRISK3 Instance 1 computation pipeline using UK Biobank baseline data.

Includes:

• Structured variable derivation
• Clinical condition flag construction
• MICE imputation framework
• QRISK3 10-year risk computation
• Documentation of derivation logic
• Reproducibility instructions

This release corresponds to the version used in the retinal AI benchmarking study.