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.
Drops dead code across services, models, utils and widgets, including the
connection auth service, which had no implementer, and the Live TV DVR
provisioning models, which had no caller.
Tests that only covered deleted behaviour are removed or trimmed. No
behaviour change.
edde746