Support Ring-MQTT activity timestamps

[thomasgregg]

Summary

Make Ring View’s existing last-activity display work with Ring-MQTT Ding and motion binary sensors while preserving the same card and viewer layout.

What changed

• Allow binary_sensor.* in the Last activity selector.
• Read only Ring-MQTT’s supported activity attributes: lastDingTime, lastMotionTime, lastDing, and lastMotion.
• Treat the configured MQTT binary sensor as the device anchor and inspect available same-device MQTT binary-sensor siblings.
• Display the freshest valid Ding or motion timestamp.
• Use the shared resolver in the dashboard card, fullscreen viewer, update checks, and configuration validation.
• Update English/German editor help and configuration documentation.

Edge cases covered

• ISO timestamps, Unix seconds, and Unix milliseconds.
• User-renamed Ding and motion entities.
• A newer activity timestamp on a sibling sensor.
• An unavailable selected anchor with an available same-device sibling.
• Missing entity-registry data.
• Invalid or unrelated attributes.
• Ring-MQTT Info sensors.
• Home Assistant last_changed and last_updated, which are intentionally not treated as activity time.

The visual editor schema and card design do not vary by provider.

Verification

• npm test -- --run — 163 tests passed.
• npm run check — passed.
• npm run build — passed.
• npm run test:browser — 112 tests passed on phone and desktop.
• git diff --check — passed.

Stack

PR 2 of 5. Base: codex/ring-mqtt-parity-foundation.