Reflow the deck into two categorical rows plus a double-height MASTER bus deck

Row membership is now the group's own property, not a wrap outcome. FILTER's Band|Notch moves to its caption slack, which is what makes the sound row fit. MASTER gains the limiter toggle, the output meter and the GR lamp.

src/shell/instrument/CLAUDE.md

@@ -12,7 +12,7 @@ The pure engine/geometry core this shell wraps (`sampler_core`, `pitch_shift`,
 `sample_chrome`, `keyboard_strip`, `waveform_view`, `loop_marks`, `capture_browser`, `browser_scroll`,
 `param_slider`, `param_taper`, `trigger_seam`, `velocity_curve`, `embed_strip`, `knob_deck`,
 `deck_groups`, `deck_values`, `bake_hold`, `curve_popup`, `spline_edit`, `master_gain`,
-`limiter`, `meter_ballistics`, `reasampler_uid.h`) lives in `core/instrument/*` and
+`limiter`, `meter_ballistics`, `master_meter`, `reasampler_uid.h`) lives in `core/instrument/*` and
 `core/wire` and is documented there — this directory consumes it but does not own it.
 
 ## Invariants
@@ -124,6 +124,13 @@ declared ahead of the instrument slots at that member in `reasampler_processor.h
   the very instance whose frame is on the stack. Deferring by one tick is same-thread and
   in-instance — it is NOT a cross-process poller/nonce handshake, and it must not grow into
   one.
+- **The MASTER meter's ballistics ride the sync tick, and that tick is 500 ms.** They run
+  BEFORE the tick's in-flight-drag guard on purpose — a drag suppresses the reload poll, but
+  the bus keeps sounding. Elapsed time is measured (`GetTickCount64`), never assumed from the
+  timer's period, and the tick repaints only when `meterDrawEqual` says the picture changed.
+  At that cadence the bar falls 10 dB per redraw and the 1.5 s hold spans three frames:
+  correct against `meter_ballistics`' contract, coarse to the eye. A meter-rate timer is a
+  separate change and is not in yet.
 - The bake's availability probe runs on the SAME tick that paints the button, so the
   control can never be enabled on one tick and refuse on the next. The bake Hold control's
   applicability (`resolveBakeHoldNeeded`) rides the same tick for the same reason, and