fix(coinfall): the tube looked broken because it was, all the time
The composite bleed sat at 0.65 texels with nothing scaling it, so every edge in
the game carried a red/cyan split from the first frame to the last. That is what
reads as 'the corruption is a rendering bug' - it was never corruption, it was
the baseline, and it never turned off. 0.65 -> 0.12, with glow, scanline and
vignette pulled back to match.
The hall was also too dark to see what is in it. It is dressed with 42 wall
cabinets, 10 bays, a change booth, a patterned carpet and ceiling fixtures, and
at the old gain a player could make out one machine and nothing else - which is
why it read as an empty corridor. Hall gain 1.0 -> 2.4, lamp reach 9 -> 11.
