Taproot Support and Python 3 Migration

[gorkapb]

Summary

• Detect native Taproot outputs and surface them throughout the status analysis pipeline (UTXO dumps, pie charts, filtered reports).
• Modernize the analysis utilities for Python 3: switch to urllib.request, replace decode/encode('hex') calls, and migrate all output to print() functions.
• Clean up presentation and correctness issues: fix decode_varint usage in transaction parsing and refine plotting styles/tick labels.