KI-15: Remove unused now variable

Dead code in services/treasury/provisioning.py:

• now = datetime.now(timezone.utc) declared but never used
• Also drops the now-unused datetime import

KI-16: Add structured logging to treasury CLI

The treasury CLI (services/treasury/cli.py) uses print_json for output but has no structured logging. In production, a logger helps trace proposal attempts, failures, and approvals.

Changes

• services/treasury/provisioning.py: logger.error() on location-not-found; logger.info() on proposal creation and approval transitions
• services/treasury/cli.py: logger.info() on agent proposal and human approval commands; logger initialized at module level

Verification

• All 30 treasury tests pass
• Syntax check clean