[lotooo]

Album art fails to load on Music Assistant 2.10+: MA replaced the
/imageproxy?path=&provider= form with /imageproxy/<proxy_id> and removed the
old one, so every artwork request now returns HTTP 400.

getImageUrl() now uses proxy_id when the server sends it and keeps the legacy
query form as a fallback, so the same build works against pre- and post-2.10
servers with no version check.

Details

Root cause — in MA 2.10.4 (controllers/metadata/images.py) the only
registered route is /imageproxy/*, and handle_imageproxy() requires a
64-char hex id taken from MediaItemImage.proxy_id. A request to
/imageproxy?path=…&provider=… never matches the /imageproxy/ prefix and
returns a bare 400 with an empty body — which is exactly what the app logs:

Error loading artUri: HttpException: Invalid statusCode: 400,
uri = https://<server>/imageproxy?provider=deezer--…&size=512&fmt=jpeg&path=https%3A%2F%2Fcdn-images.dzcdn.net%2F…

Sizes — MA only accepts {0, 80, 160, 256, 512, 1024} and 400s on anything
else. Call sites in this repo pass 80, 128, 256 and 512, so 128 would have
failed; _imageProxySize() rounds up to the nearest accepted value.

The two re-host sites in music_assistant_provider.dart rebuilt a URL as
'$baseUrl/imageproxy?$queryString', keeping only the query and discarding the
path. Given a 2.10 URL that collapses /imageproxy/<id>?size=512 to
/imageproxy?size=512, another 400. They now preserve imgUri.path, which is
equivalent to the old behaviour on pre-2.10 servers.

Verified against a live MA 2.10.4 server (schema 65). Using a real
proxy_id pulled from player_queues/all:

URL	Result
/imageproxy/<proxy_id>?size=512&fmt=jpeg	200 image/jpeg, 21 982 b
/imageproxy/<proxy_id>?size=128 (unclamped)	400
/imageproxy?path=…&provider=… (before this PR)	400, empty body

Clamped sizes 80/160/256/512 all return 200. Not compile-checked — no Flutter
toolchain was available where this was written.