PLN opened fred_angie_bass, the first kit he tried, and found two bad loops
immediately: ":0 starts, then silence, then starts again" and ":2 why is this
not trimmed, silence before silence after?". Both had shipped as tier S with
zero flags, one at grade 0.991.

He was right, and it is worse than two files. Binning each loop's envelope on
its own beat grid says 12 of 111 loops carry dead air — and 5 of 14 bass loops,
36%, which is why he hit it on his first click. angie:0 has beats 7-9 of 32 at
-88 dBFS; bighen_bass:1 has a five-beat hole and 62.5% occupancy at grade 0.983.

This is the third time this session that silence beat the grader, and the
reason is the same each time, one level further down. Silence-as-optimum was
fixed at export, then again in the finder before ranking, but every one of those
checks is an AGGREGATE: file peak, whole-file RMS, max of the beat table. An
aggregate cannot see a hole. A loud loop with a silent bar inside it passes all
three. And kitcheck's dead-bar rejector looks at BARS, so a 2.5-beat gap
straddling a bar boundary is invisible — angie:0's two bars read -18.3 and
-15.9 dBFS while the beats between them read -88. Resolution was a correctness
input and I had treated it as a detail.

So this commit does not fix it, it measures it. beatocc.py bins the envelope on
the loop's own beat grid (bpm and bars from the manifest, never re-estimated)
and reports SHAPE rather than level: head and tail dead beats, longest interior
dead run, occupancy, plus a beat map under -v. It exits non-zero when any loop
has dead air, so it can go straight into kitgate once the thresholds are known.

Thresholds deliberately not chosen yet. Occupancy floors have to be per family
like the periodicity floors — marea_vox/06_breaths_1b at 25% occupancy is a
breath, not a defect, while a bass loop at 62% is broken — and the head-silence
question has three plausible answers (trim, rotate, reject) with rotation ruled
out already, since angie:2's offset is 1.17 beats and _rotate_to_downbeat snaps
to beats. Placing those floors by guess is how silence got graded A in the first
place. #24 on the board carries the open decisions and the data needed for each.

The Fred pack section is now marked DEFECTIVE rather than SHIPPED. It needs a
re-cut once the shape check exists, and PLN's verdict stands as written:
"tbh i dont think the loops are usable."