Improve detection telemetry readiness gates

[MAUROCERON]

Implements #1417.

Summary

• Adds a telemetry readiness and rule-health evidence gate before counting detection coverage as operational.
• Adds an output matrix tying ATT&CK data components, Sigma logsource, backend target, collector health, parser fields, rule status, suppressions, retention, and coverage decision.
• Adds edge-case fixtures for stale log sources, parser drift, disabled/failing analytics rules, overbroad suppressions, insufficient retention, and complete healthy telemetry paths.

Validation

• Checked Markdown fence balance for the updated skill and new fixture.
• Verified required markers: Telemetry and rule-health evidence gate, Collector/connector health, Parser and field mapping, Rule deployment health, Suppression and exception scope, Not Evaluable.
• Verified MITRE ATT&CK, Sigma, and Microsoft Sentinel reference URLs return HTTP 200.

Payment details can be provided privately after maintainer acceptance.