feat(chain): Add min_confirmations parameter to CanonicalView::balance

feat(chain): Add min_confirmations parameter to CanonicalView::balance

Add min_confirmations parameter to control confirmation depth requirements:
- min_confirmations = 0: Include all confirmed transactions (same as 1)
- min_confirmations = 1: Standard behavior - require at least 1 confirmation
- min_confirmations = 6: High security - require at least 6 confirmations

Transactions with fewer than min_confirmations are treated as trusted/untrusted
pending based on the trust_predicate. This restores the minimum confirmation
functionality that was available in the old TxGraph::balance doctest but with
a more intuitive API since CanonicalView has the tip internally.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>