These are stems from a loud commercial master — MAREA's ALL DRUMS and KIT both peak at
+0.2 dBFS — so a loop cut from them arrives at full scale. grade already calls that
clipping, and SuperDirt cannot use it: amp = gain^4, so `# gain 1.2` is +7.6 dB and the
orbit clips the moment you touch it. The house rule is peaks at -6 dBFS at the source and
let the amplification happen downstream, so that is where kits land now.

Two decisions inside kit_headroom_gain that matter more than the ceiling:

NOT per file. One scalar for the whole kit. Normalising each file on its own would make a
sparse hat loop exactly as loud as a full drum bus, throwing away the balance that two
loops from one kit otherwise have for free — the reason to cut a kit from one track in
the first place.

NEVER boosts. A kit already below the ceiling is left exactly where it is. A quiet stem
is quiet on purpose; lifting it amplifies its noise floor and discards real information
about the arrangement.

restage.py applies the same function to kits already on disk, so a kit restaged after the
fact is bit-identical to one cut with it in place. Useful beyond this pack: hand-cut kits
carry whatever level their source had, and there are 163 kits in Samples/.

It also re-grades the manifest for anything it changed. Whoever moves the audio owns the
record of it — every grade has a level term, so a stale manifest describes bytes that no
longer exist, and kitgate compares the two precisely to catch that drift. Verified on the
synthetic pack: clipping cleared, two drum loops A -> S, and the gate then caught the
stale grades until restage started writing them back.

23 tests in the file.