pixel.png: a plain white 32x32 square, generated by
devtools/generate_icons.py (not hand-drawn -- re-run that script if this
ever needs regenerating). Registered as the `uplink-vision-glitch-pixel`
sprite prototype (prototypes/vision-glitch.lua) and recolored per-cell at
runtime via `.tint` to build the pixelated "degraded feed" grid effect in
scripts/vision-glitch.lua -- one base image, many colors, the same
technique the base game uses for biter/spitter recoloring.

v0.19.0: this replaced an earlier flat, near-opaque grey overlay (a
tinted vanilla frame background, no real pixelation) that was reported as
low-effort/boring. If you want to go further than a generated flat-color
grid -- e.g. a genuinely hand-drawn static/noise texture -- the swap
point is prototypes/vision-glitch.lua's `filename` field; the runtime
code in scripts/vision-glitch.lua doesn't need to change either way.
