Remove duplicate calculate_limits() and utility functions

[cnicholas]

The calculate_limits() function and related utilities are defined identically in two files:

• analysis_dataset.py:1665-1734
• objects.py:81-195

The code uses obj.calculate_limits(), so the local versions are never used.

Duplicate Functions

• calculate_limits()
• c4()
• b3()
• b4()
• detect_beyond_limits()

Impact

• Maintenance risk (changes in one place won't reflect in the other)
• ~70 lines of duplicate code
• Confusion about which version is canonical

Fix

Remove calculate_limits(), c4(), b3(), b4(), and detect_beyond_limits() from analysis_dataset.py (lines 1665-1734). Keep only versions in objects.py.

Files

• analysis_dataset.py
• objects.py