Support private openHAB Cloud instances via proxy URL discovery

[timbms]

Summary

Fixes #729

• Resolve cloud proxy URL dynamically via GET /api/v1/proxyurl instead of hardcoding myopenhab.org → home.myopenhab.org rewrites
• Replace hostname-based auth checks (hasSuffix("myopenhab.org")) with the supportsNotifications configuration flag across all auth middleware
• Delete dead SessionChallengeHandler class (never instantiated)

What this enables

• Private cloud users: Configure their cloud URL (e.g., https://cloud.example.com) with "openHAB Cloud Service" toggle on → app calls /api/v1/proxyurl to discover the correct web UI URL
• Official myopenhab.org users: Same flow — endpoint returns https://home.myopenhab.org:443, falls back gracefully if unavailable
• Local-only connections: Unaffected — supportsNotifications is false, proxy URL is never fetched

Files changed

File	Change
NetworkTracker.swift	Add proxyURL to ConnectionInfo, add fetchProxyURL() helper, resolve after connection test
OpenHABWebViewController.swift	Use proxy URL in modifyUrl(), use supportsNotifications flag for cloud detection
SessionChallengeHandler.swift	Use proxy URL host for auth challenges, delete dead class
AuthorisationMiddleware.swift	Use supportsNotifications instead of hostname check
HTTPClient.swift	Use supportsNotifications instead of hostname check
OpenHABAccessTokenAdapter.swift	Use supportsNotifications instead of hostname check

Test plan

• Build succeeds (verified)
• Unit tests pass (verified)
• Manual: configure https://myopenhab.org as remote → verify proxy URL is fetched and web view loads home.myopenhab.org
• Manual: configure a private cloud URL with "openHAB Cloud Service" enabled → verify proxy URL API is called and returned URL is used
• Manual: disconnect or use invalid cloud URL → verify graceful fallback
• Manual: local-only connection (no remote) still works without proxy URL fetch

[digitaldan]

I know supportsNotifications is part of the existing stored preferences, but i wonder if for future proofing this we create a property on the active config for isCloudConnection or something like that. For the time being it can internally check if supportsNotifications is true or not, but then the rest of the code does not have to depend on this preference name which is confusing to read (and i totally understand i probably wrote that hack in the first place) .

[timbms]

I could  also update the Preferences filter to use isCloudConnection. @digitaldan : Let me know

[digitaldan]

Whatever you think is best 👍

[timbms]

For the moment I would leave it as is. We could change it when we redo the Preferences loading to become more flexible.

[timbms]

@digitaldan: who could test it? I am not running a private openHAB Could instance.

[digitaldan]

I can test it, but it should work exactly the same with out production service, right? It will pull the proxy host from the api? I'm actually working on a huge migration to typescript on the cloud service right at this moment so can give it a try since i have that up and running.

[digitaldan]

I can test it, but it should work exactly the same with out production service, right? It will pull the proxy host from the api? I'm actually working on a huge migration to typescript on the cloud service right at this moment so can give it a try since i have that up and running.

[digitaldan]

I can confirm this works with a custom server 👍

[timbms]

Can we merge it?