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.
Shared TabChipStrip replaces the plain Rows in libraries/downloads/live
TV app bars (and live TV's hand-rolled scroll wrapper); chips center
themselves on focus so d-pad reaches off-screen tabs.
edde746