Cycle-driven TIA beam model: scanlines advance every 76 CPU cycles, not only at WSYNC

The snapshot pipeline captured TIA state only in the WSYNC handler. Kernels that race the beam without WSYNC (Space Invaders' 6-invader rows: mid-scanline GRP0/GRP1 rewrites with PHA/PLA cycle padding, 2 scanlines per iteration, zero WSYNCs; every title's INTIM-paced VBLANK/overscan) starved the snapshot ring (SI: 77 snapshots vs 262 real lines) and the screenshot path extrapolated the last captured snapshot down the screen — SI's lower 2/3 was a solid…

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