README: regenerate the family footer for family-os v0.20.0 (sibling sweep)

[shojikumaru]

Why

family-os v0.20.0 (https://github.com/caty-ai/family-os/releases/tag/v0.20.0) added two published modules to the map: errmeter and caty-gateway. Every family README carries a generated footer that lists the map, so each sibling repository needs its footer regenerated — otherwise the scheduled family footer check reports "the map no longer matches reality". This is the mechanical sibling sweep from the family-footer contract's Publication Runbook (family-os docs/family-footer-contract.md).

What changed

Only the generated region between <!-- family:generated:family-footer:start --> and <!-- family:generated:family-footer:end --> in the declared README*.md files, rendered by python3 -B tools/family_footer.py render-all from family-os main @ v0.20.0. No hand edits; a second render is a no-op (idempotent).

Verification

• Rendered from the registry at family-os v0.20.0; byte-exact output is what the scheduled check compares against.
• Repo CI on this PR.

Completion record (L1-7)

• Done when: footer region equals the v0.20.0 render — PASS (idempotent second render)
• Implementer: alpha (Claude Code) · Review: mechanical generated-content PR per the Publication Runbook (registry PR #174 itself had 3 heterogeneous seats × 3 rounds); CI green required before merge
• release: N/A (generated README footer only; no behaviour, API or distributed artefact change)

🤖 Generated with Claude Code