fix: use modern Jellyfin authorization

app/services/jellyfin.py

@@ -1,9 +1,20 @@
 import httpx
 from app.config import settings
 
-_headers = {
-    "X-MediaBrowser-Token": settings.jellyfin_api_key,
-}
+
+def _authorization_header(token: str | None = None) -> str:
+    values = [
+        'Client="Movie Night"',
+        'Device="Web"',
+        'DeviceId="movie-night-app"',
+        'Version="1.0.0"',
+    ]
+    if token:
+        values.insert(0, f'Token="{token}"')
+    return f"MediaBrowser {', '.join(values)}"
+
+
+_headers = {"Authorization": _authorization_header(settings.jellyfin_api_key)}
 
 _client: httpx.AsyncClient | None = None
 
@@ -22,14 +33,11 @@ def _get_client() -> httpx.AsyncClient:
 async def authenticate_user(username: str, password: str) -> dict | None:
     """Authenticate a user via Jellyfin. Returns user info + token or None."""
     client = _get_client()
-    auth_header = (
-        'MediaBrowser Client="Movie Night", Device="Web", DeviceId="movie-night-app", Version="1.0.0"'
-    )
     try:
         res = await client.post(
             "/Users/AuthenticateByName",
             json={"Username": username, "Pw": password},
-            headers={"X-Emby-Authorization": auth_header},
+            headers={"Authorization": _authorization_header()},
         )
         if res.status_code == 200:
             data = res.json()