docs: add local runbook for ctf-exchange

[Angel1945uwu]

Added a concise runbook that explains how to start, verify, and reset the CTF exchange locally.

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Note

Adds concise documentation to run and validate the CTF exchange locally.

• New docs/local-runbook covering startup order, health verification, common failure modes, and steps to reset local state
• No code changes; documentation-only addition

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