Bake window: derived note lengths carry exact durations, not ladder rungs — a long take is no longer cut at 384 beats

Hold keeps its picker. Also: one home for the %-fold, duration-ordered Hold travel, and a corrupt tail degrades to absent rather than fabricating one.

tests/test_sample_chrome.cpp

@@ -128,9 +128,9 @@ static void testVelocityKnobIsCentredInItsCellAboveTheLabel() {
     CHECK(r.velLabel.x == r.velCell.x && r.velLabel.right() == r.velCell.right());
 }
 
-// The Hold cell reserves its width whether or not the control is drawn — a run laid out
-// conditionally would slide Bake and Preview out from under the pointer whenever a loop is
-// dialled in or out. Its interior follows the velocity cell's grammar exactly.
+// The Hold cell reserves its width whether or not the control is drawn, so the title slot
+// beside it holds still (sample_chrome.h owns the reasoning). Its interior follows the
+// velocity cell's grammar exactly.
 static void testHoldCellIsReservedAndFollowsTheVelocityCellGrammar() {
     const ChromeRects r = chromeRects(chromeBand(), kKnob);
     CHECK(r.holdCell.width == r.velCell.width);