feat(bank_panel): docked bank grid with LICE waveform thumbnails (M5 Wave A)

Docked SWELL window toggled by a new action, drawing the current bank as
per-sample min/max thumbnails (PCM_source + peaks) with an in-memory cache.
Pure grid-layout/cache-key math in bank_grid (tested). Renames peaks::Sample
-> AudioSample to avoid colliding with bank_model::Sample.

src/peaks.h

@@ -13,18 +13,23 @@
 
 namespace reasampler {
 
-// Canonical in-memory sample type. `float` is REAPER's native audio buffer format
-// (its render/PCM_source callbacks hand back interleaved 32-bit float), so peaks
-// consumes that directly with no lossy conversion. If a capture ever lands as a
-// different depth, the caller converts to float at the boundary — the thumbnail
-// core stays single-typed.
-using Sample = float;
+// Canonical in-memory audio-sample type. `float` is REAPER's native audio buffer
+// format (its render/PCM_source callbacks hand back interleaved 32-bit float), so
+// peaks consumes that directly with no lossy conversion. If a capture ever lands
+// as a different depth, the caller converts to float at the boundary — the
+// thumbnail core stays single-typed.
+//
+// NAMED AudioSample, not `Sample`: `reasampler::Sample` is already bank_model's
+// metadata struct. A `using Sample = float` here would collide at namespace scope
+// wherever both headers are visible (the bank_panel module includes both). The
+// audio-domain name also reads more precisely — this is one PCM sample value.
+using AudioSample = float;
 
 // One bin of a channel's envelope: the extremes of every sample that fell in it.
 // min <= max always. For an empty bin (more bins than frames), both are 0.
 struct MinMax {
-    Sample min = 0.0f;
-    Sample max = 0.0f;
+    AudioSample min = 0.0f;
+    AudioSample max = 0.0f;
 
     bool operator==(const MinMax& o) const { return min == o.min && max == o.max; }
 };
@@ -56,7 +61,7 @@ using Envelope = std::vector<ChannelEnvelope>;
 //   binCount == 0     -> per channel: an empty bin vector.
 //   channelCount == 0 -> an empty envelope (no channels).
 //   frameCount == 0   -> per channel: binCount bins, all {0, 0}.
-Envelope computeEnvelope(const std::vector<Sample>& interleaved,
+Envelope computeEnvelope(const std::vector<AudioSample>& interleaved,
                          std::size_t channelCount,
                          std::size_t frameCount,
                          std::size_t binCount);