When a user enters an http:// Immich URL that redirects to https://,
the test succeeded (GET follows redirects fine) but subsequent POST
requests (e.g. photo search) broke due to method downgrade on 301/302.
Now testConnection() checks resp.url against the input URL after a
successful fetch. If the only difference is http→https on the same
host and port, it returns a canonicalUrl so the frontend can update
the input field before the user saves — ensuring the correct URL is
stored.
Marek Maslowski