8 test files had _DummyConfigManager missing get_active_media_server(),
causing failures when pytest ran them before the test file that had it.
Whichever file set sys.modules first won, and the incomplete dummy broke
later tests. Also fix script.js read_text() missing encoding='utf-8'
which failed on non-UTF-8 default locales.
Respect the configured metadata source order when looking up album years, and re-check provider availability during the scan so Spotify can drop out cleanly if it becomes rate-limited.