Feat: overhaul to produce .dmg and .app on macOS build script

docs/engine/samples.md

@@ -45,6 +45,8 @@ snare sound  0.5 speed .         ( play snare at half speed )
 | `n` | 0+ | Sample index within a folder (wraps around) |
 | `begin` | 0-1 | Playback start position |
 | `end` | 0-1 | Playback end position |
+| `slice` | 1+ | Divide sample into N equal slices |
+| `pick` | 0+ | Select which slice to play (0-indexed, wraps) |
 | `speed` | any | Playback speed multiplier |
 | `freq` | Hz | Base frequency for pitch tracking |
 | `fit` | seconds | Stretch/compress sample to fit duration |
@@ -62,6 +64,21 @@ kick sound 0.5 end .               ( play first half )
 
 If begin is greater than end, they swap automatically.
 
+## Slice and Pick
+
+For evenly-spaced slicing, `slice` divides the sample into N equal parts and `pick` selects which one (0-indexed, wraps around).
+
+```forth
+break sound 8 slice 3 pick .          ( play the 4th eighth of the sample )
+break sound 16 slice step pick .      ( scan through 16 slices by step )
+```
+
+Combine with `fit` to time-stretch each slice to a target duration. `fit` accounts for the sliced range automatically.
+
+```forth
+break sound 4 slice 2 pick 1 loop .   ( quarter of the sample, fitted to 1 beat )
+```
+
 ## Speed and Pitch
 
 The `speed` parameter affects both tempo and pitch. A speed of 2 plays twice as fast and an octave higher.