v3.12.9 — HACS compliance

✅ HACS default repository readiness

This release fixes validation issues for HACS default repository submission:

• hacs.json now contains only allowed keys
• strings.json / ru.json no longer contain raw URLs (hassfest requirement)
• manifest.json has codeowners set
• GitHub topics and Actions (HACS validation + Hassfest) added

No user-facing changes.

Update via HACS

HACS → SMS Gammu Viewer → Update, then restart Home Assistant.