PageUp and PageDown are the volume knob

The cabinets had no volume control - they ran at unity and left level to an
external amplifier - so a player without that hardware had nowhere to turn
it down but environ.ini and a restart. PageUp and PageDown now step the
master volume by 0.05 while you play, from silent to double, and whatever
you leave it on is written to volume.cfg beside the exe and used from then
on. The environ.ini figure decides where a machine that has never been
touched starts out; the keys are the knob, and a knob stays where it was
left.

Page keys because they produce no typed character, so they cannot collide
with the character-keyed commands the engine already answers to, nothing
else in RP binds them, and they are on every keyboard including tenkeyless.

They are polled rather than read off the key-message path, which is worth
recording because the message path looked like the obvious home for them
and was tried first. RP's keyboard pump only takes WM_KEYUP, WM_SYSKEYUP
and WM_CHAR off the front of the queue, and the front end runs message
loops of its own, so key messages get raced for and lost: six deliberate,
well-spaced presses arrived as two. Fine for the abort chord, useless for
something you tap repeatedly to find a level. Reading key state directly
costs nothing and cannot be dropped. That losses figure is a pre-existing
property of the input path, not something this change introduced, and is
worth knowing before anything else gets bound there.

Builds clean, runs, and does not fire unprompted. The step function itself
is proven - it was driven end to end through the message path before the
switch, stepping the right way, clamping, and persisting. What I could not
test from here is the polling trigger, because Windows would not hand the
game foreground and injecting keys without it would have sprayed them
across whatever else was open.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

RP_L4/RPL4ENVIRON.cpp

@@ -234,10 +234,15 @@ namespace
 "# certainly have neither, so these two stand in for them. Both default\n"
 "# to leaving the mix exactly as the pod played it.\n"
 "\n"
-"# Master volume, 0.0 to 4.0, the amplifier's knob. 1.0 is unity. The\n"
+"# Master volume, 0.0 to 2.0, the amplifier's knob. 1.0 is unity. The\n"
 "# sound effects now carry the pitch, layering and dynamics the original\n"
 "# AWE32 soundbanks ask for, which is a good deal livelier than earlier\n"
 "# 4.12 builds - lower this if the whole thing sits too hot.\n"
+"#\n"
+"# PageUp and PageDown change it while you play, in steps of 0.05, and\n"
+"# whatever you leave it on is written to volume.cfg beside the exe and\n"
+"# used from then on - so this line only decides where a machine that has\n"
+"# never been touched starts out. Delete volume.cfg to come back here.\n"
 "#RP412AUDIOVOLUME=0.8\n"
 "\n"
 "# Bass trim, 0.0 to 1.0, the crossover's low band. 1.0 is the low end\n"