Add Cadence Quality metric with debug instrumentation

[ivyztech]

This PR introduces an experimental Cadence Quality (CQ) metric.

• Adds CQ computation using time-in-zone and cadence smoothness
• Includes warm-up window and final score freezing
• Adds debug and diagnostic logging for traceability
• Keeps implementation within Watch App constraints

This is intended as a research-aligned exploratory feature.

[github-actions]

🔒 Security Scan Results

🔒 Security Scan Results
=========================

Bandit Scan Results:
-------------------
Run started:2026-01-16 18:22:19.287025+00:00

Test results:
	No issues identified.

Code scanned:
	Total lines of code: 0
	Total lines skipped (#nosec): 0
	Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
	Total issues (by severity):
		Undefined: 0
		Low: 0
		Medium: 0
		High: 0
	Total issues (by confidence):
		Undefined: 0
		Low: 0
		Medium: 0
		High: 0
Files skipped (0):

✅ No critical security issues detected.

The code has passed all critical security checks.

[RamGcia]

looks good