Sanitize public documentation surface

[valiantone]

Summary

• Remove internal YC/session-trace, OKF planning, Hermes campaign, documentation-service, and root planning artifacts from the public tree.
• Replace them with a concise public architecture overview and current-capability documentation.
• Remove proprietary stack references from runtime messages/comments/tests and delete generated manifests containing machine-specific paths.

Why

The docs site was ready to publish but exposed internal processes, unrelated implementation planning, and proprietary architecture boundaries. This keeps the public docs focused on shipped HotMem behavior.

Validation

• uv run --locked --extra docs mkdocs build --strict
• uv run ruff check src/ tests/
• uv run pytest -q — 389 passed, 6 skipped
• Residual scan of the repository and generated site for removed sensitive terms and paths

Note

This sanitizes the current tree. Previously published Git history is unchanged and would require a separate reviewed history rewrite if needed.