Add IR communication channel integrity gates

[yanziwei]

Summary

Closes #1680.

• Adds a communication channel integrity gate to ir-playbook.
• Adds IR-COMMS findings for attacker-visible channels, missing out-of-band triggers, unverified war-room participants, untraceable containment orders, sensitive evidence in compromised channels, missing access records, and unsafe return to normal channels.
• Extends the report template with a communication channel integrity evidence table.
• Updates the existing attacker-alerting pitfall with explicit authorization, membership, order channel, and return-to-normal evidence requirements.
• Updates the skill version to 1.1.0.

Validation

• git diff --check
• Markdown fence balance check: 16 balanced
• Verified markers for version 1.1.0, Communication Channel Integrity Gate, IR-COMMS-01, output table, and return-to-normal criteria

Bounty request

Improver Moderate / $100 if accepted. Payment details can be provided privately after maintainer acceptance.