[SPR] sprite row-window telemetry (GRP first/last scanline vs logic Y)

Instrumentation finding serving the F108v2 diagnosis (residual ~20-row era-dependent sprite-vs-logic vertical drift, sprite channel only). tia_publish_frame_truth() now tracks, per frame, the first/last visible scanline where GRP0 and GRP1 were nonzero plus the frame first-visible scanline (the F104 anchor), exposed via tia_grp{0,1}_{first,last}_sl() / tia_first_visible_sl().

Raw traces, ROM material, local paths, and personal data are not part of this public record.