Part of the #180 library picker fixes (SPA side).
Channel builder: TelevisionSeason is removed from the library grid fan-out, so a
multi-season show renders as one tile instead of one tile per season. Show tiles
gain a "Seasons" drill-in affordance (both grid and compact layouts) that opens a
dialog listing that show's seasons (via the new GET /api/library/browse?parentId=
&mediaType=TelevisionSeason), each with title, artwork and an Add button that
drops the specific season into the lineup.
Collections add-items dialog: the default search fan-out now excludes seasons,
and a media-kind filter row (All / Movies / Shows / Seasons / Artists,
default = All-without-seasons) keeps seasons reachable when explicitly selected.
Client: getLibraryBrowseItems gains an optional parentId param. Tests cover the
param mapping, the builder no longer requesting TelevisionSeason, and the
collections dialog default-excluding vs explicitly-including seasons.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>