Explain Relay operation from deployer tasks

[Raphjacksun7]

Purpose

Make the Relay README and guides usable without internal project context. Explain credential ownership, named bus publication, subscription, control-state reconciliation, deployment, capacity, and recovery from the operator's task.

Verification

• Markdown links resolve locally.
• The public-language scan has no unexplained architecture shorthand.
• Documentation-only change; Relay media behavior is unchanged.

Evidence limits

The guide distinguishes synthetic transport verification from physical capture, and same-host checks from WAN, TURN, and load qualification.

Staff review

1. Purpose and files changed: README plus Relay guides.
2. Product result: operators can configure and verify Relay from one documented route.
3. Architecture affected: none.
4. Tests and evidence: documentation and link checks only.
5. Remaining scaffold/mock/loopback behavior: the test source is identified as synthetic.
6. Scaffold inventory update: not applicable.
7. CODE_PROTOCOL review: pass.
8. Decision: PASS.