docs(requirements): add 004 radio set

The Agent Orchestrator radio as a minimalist marine VHF set: a server CPU gate for speech, a WebAudio noise burst, modes Auto, Quiet and Silence, procedure words that always sound, every radio setting in the panel and a log with Sent, Received and All plus filters. Operator decisions 2026-11-12.

🎯 Fix: 95 %
💥 Break: 1 %
💸 Cost: 100 %
⏱️ Time: 100 %
🛡️ Security: 100 %
🏆 Score: 94
🚦 Gate: ✅ 90/5, cost and time <= 100, security 100 %

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/requirements/README.md

@@ -7,3 +7,4 @@ skill defines the format.
 - [001 - Agent Orchestrator](001-agent-orchestrator.md)
 - [002 - Cosmos](002-cosmos.md)
 - [003 - Operator Workbench](003-operator-workbench.md)
+- [004 - Radio Set](004-radio-set.md)