OpenCoven Hook Adapter Adds V0 Safety Prototype

OpenCoven Hook Adapter v0 moved from research into executable safety prototype territory.

Highlights:

• Added executable hook-entrypoint coverage for protected-path decisions.
• Documented the living control map, RFC, prototype brief, and live smoke recipe.
• Verified local safety behavior for protected files such as .env and MEMORY.md.
• Clarified that Hook Adapter v0 covers lifecycle, policy, approvals, and audit events around harness activity.