Fix for UGOS not updating sensors without active Web GUI or App

👉 For end users (please read!!!)

This Update will fix the problem that UGOS/HA isn't updating some of it's API end points when there is no active session through UGOS Web GUI or UGOS app.

❗ A code pull / re-deployment of the UGREEN API Token Proxy container on your NAS is highly recommended (takes ~2 minutes).
❗ Only updating the Home Assistant integration will work, but you won’t benefit from this fix without redeploying the container.

Beta testers (@rexprojects, @Sineiko, @Danoro821973):
Thank you, your help is much appreciated! 🙌
Make sure you switch your Docker Compose back from :develop to :main before pulling.

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👉 For developers / internal changes

Docker container

• Add ws_keepalive.py implementing a persistent WebSocket connection to UGOS
• Add PyYAML to requirements
• Install tzdata; limit Playwright dependencies to Chromium
• Add TZ (timezone) to the environment so logs use local time
• Add LOG_LEVEL (e.g., info, debug) to the environment
• Harmonize logging across the container
• Implement new /credentials endpoint as the single source of truth
• Add comments to all files for better readability

HA integration

• Add _push_credentials_to_proxy in api.py to periodically send credentials (and token, if present) to the proxy for the WebSocket keep-alive