Add GW1200 AC1100 smart plug discovery and control

[mot-yelraf]

Summary

Add discovery, status reporting, and control for AC1100 smart plugs paired with a GW1200. Add Device now offers Find Devices, Discovered GW Sensors, and a separate Discovered GW Smart Plugs list with a 15–60 second query interval (default 30).

Plugs use the existing dashboard switch cards, editable locations and labels (default Plug), timers, and Advanced automations. Commands trigger status confirmation; event history records observed states without duplicate restart or toggle events. Home Assistant also waits for confirmed state. Weather polling remains independent, and existing MQTT switch behavior is preserved.

Update canonical documentation, factory defaults, and version to v0.26.253.1.

Verification

• macOS, Python 3.13.9; simulated local HTTP gateway responses, no physical GPIO, GW1200, AC1100, or live MQTT broker.
• Focused pytest suite for Ecowitt discovery/parser/routes/switches, switch controllers/factory/settings, automations, Home Assistant, and Python compilation: 168 passed, 1 skipped.
• npm run validate:pr: 24 Chromium checks passed using the isolated host fixture, including AC1100 discovery, interval saving, dashboard toggling, event list, and offline status.
• Rendered discovery and switch-card screenshots reviewed.
• git diff --check: passed.

Contributor checklist

• This pull request is focused on one logical change.
• I added or updated tests for behavior changes.
• I updated the canonical documentation when behavior or configuration changed.
• I did not commit credentials, private runtime configuration, databases, or logs.
• I preserved compatibility-sensitive MQTT, settings, switch identity, and persistence behavior, or documented an intentional break.

Maintainer verification

• Required remote checks pass (Python 3.11/3.13 compilation and full regression suite with coverage floor).
• npm run validate:pr passes on a trusted host when the change can affect rendered UI behavior.
• Hardware-, broker-, onboarding-, and platform-specific behavior not covered remotely is recorded below.

Residual risk or unverified areas

Physical GW1200/AC1100 validation is pending receipt of the AC1100. The maintainer explicitly requested merging before hardware validation. Real gateway firmware responses, radio behavior, physical relay operation, and live broker integration have not been exercised. Hardware pairing/onboarding and non-macOS runtime behavior remain unverified locally; mocked API responses cover the documented protocol. Changes occurring entirely between status queries cannot be recovered.