Extract magic numbers as constants in SCORE2

[fbraza]

Issue Description

The SCORE2 implementation contains several magic numbers that could be extracted as named constants for better readability and maintainability.

Current Magic Numbers

Transformation Constants

cage = (age - 60) / 5        # 60 and 5 are magic numbers
csbp = (sbp - 120) / 20      # 120 and 20 are magic numbers
ctchol = tchol - 6           # 6 is a magic number
chdl = (hdl - 1.3) / 0.5     # 1.3 and 0.5 are magic numbers

Risk Thresholds

if age < 50:
    if calibrated_risk < 2.5:      # 2.5 is a magic number
    elif calibrated_risk < 7.5:    # 7.5 is a magic number
else:
    if calibrated_risk < 5:        # 5 is a magic number
    elif calibrated_risk < 10:     # 10 is a magic number

Suggested Implementation

# Add at module level or as class constants
# Transformation reference values
AGE_REFERENCE = 60
AGE_SCALE = 5
SBP_REFERENCE = 120
SBP_SCALE = 20
TCHOL_REFERENCE = 6
HDL_REFERENCE = 1.3
HDL_SCALE = 0.5

# Risk thresholds by age group
RISK_THRESHOLDS_UNDER_50 = {
    'low_to_moderate': 2.5,
    'high': 7.5
}

RISK_THRESHOLDS_50_PLUS = {
    'low_to_moderate': 5.0,
    'high': 10.0
}

# Age threshold
AGE_THRESHOLD = 50

# Then use in code:
cage = (age - AGE_REFERENCE) / AGE_SCALE
csbp = (sbp - SBP_REFERENCE) / SBP_SCALE
# etc...

Benefits

• Self-documenting code
• Easier to update values if needed
• Reduces risk of typos
• Makes the algorithm parameters explicit

Impact

• Low priority enhancement
• Improves code readability
• No functional changes

Related

• PR feat: Implement SCORE2 cardiovascular risk assessment algorithm #2: feat: Implement SCORE2 cardiovascular risk assessment algorithm
• Follows coding style principle: "Use clear, descriptive names"