Remove coverage map bootstrap guidance

[chubes4]

Summary

• removes remaining coverage-map guidance from the Docs Agent consumer wrapper
• tells bootstrap runs to scaffold complete, hierarchical docs from repository source instead of producing audit artifacts
• updates fallback PR body to describe architecture-shaped digestible topic docs

Testing

• bash -n tests/playground-ci/scripts/run-docs-agent.sh
• git diff --check

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Diagnosed the stale consumer wrapper instruction that reintroduced coverage-map output and updated the CI prompt/PR body; Chris remains responsible for review and merge.