Replace magic numbers with named constants

[cnicholas]

Statistical constants are hard-coded throughout the code with no explanation or source citations.

Examples

• Line 1697: 2.66 (IMR limit multiplier)
• Line 1705: 3.268 (R chart limit multiplier)
• Line 299-300: beyond_limits calculation logic
• Various uses of 3 for sigma multipliers

Impact

• Hard to verify correctness
• No documentation of where constants come from
• Hard to modify if different sigma levels needed

Fix

Define named constants at module level with docstrings:

# Statistical constants based on d2 and d3 tables
IMR_LIMIT_MULTIPLIER = 2.66  # E2 constant for n=2 (individuals)
R_LIMIT_MULTIPLIER = 3.268   # D4 constant for n=2 (moving range)
SIGMA_MULTIPLIER = 3         # Standard 3-sigma control limits

Files

• analysis_dataset.py
• objects.py