Piped accepts the session token via either an Authorization header or an
authToken query parameter (the /feed endpoint already uses the latter form).
Switch all token-bearing Piped endpoints to the query-parameter form so the
Authorization header is free for HTTP Basic Auth from a fronting reverse
proxy. Affects subscriptions, subscribe, unsubscribe, userPlaylists, and
userPlaylist (including its nextpage pagination loop).
Malformed items in relatedStreams (e.g., missing title) no longer crash
the entire JSON decode. Reuses the existing PipedVideoItem (renamed from
PipedPlaylistItem) graceful-decoding wrapper for all relatedStreams arrays
in PipedStreamResponse, PipedChannelResponse, and PipedNextPageResponse.
Playlists only loaded the first page of videos. Add full pagination for
both Invidious and Piped playlist endpoints (public and authenticated).
Deduplicate Invidious results by playlist index to handle its overlapping
page windows. Also fix URL encoding in Invidious login to use strict
form-encoding charset.
