Introduces shared seams for paginated views, D-pad reorder, media control
routing, async singletons and the device method channel, then points the
open-coded copies at them.
Also removes unused models and duplicated provider/server plumbing, folds
the twice-implemented artifact store in the server, and factors the
repeated Flutter toolchain prologue in CI into a composite action.
Re-enables Audio Passthrough on Apple TV against the MPVKit EAC3-JOC
AVPlayer sink (pin bump to v1.0.8 follows), adds an AVPlayer test
harness + diagnostics screen for #1300, and makes loudnorm yield while
passthrough is active (fixes a latent spdif conflict on desktop too).
edde746