Loop-crossfade-ux review fixes: parked-drag no longer fakes LOOP OFF, waveform label contrast fixed, hover memoizes its bank read

Also corrects the cap-area, em-dash, glyph-overhang and heuristic-comment findings noted in review.

tests/test_sample_chrome.cpp

@@ -157,8 +157,9 @@ static void testHoldCellIsReservedAndFollowsTheVelocityCellGrammar() {
 // the agreed remedy if it cannot is to narrow the enable's segments, never to move the floor.
 static void testTheControlRunLeavesTheTitleReadableAtTheEditorFloor() {
     const ChromeRects r = chromeRects(chromeBand(), kKnob);
-    // "ReaSampler 9000" (15 chars) plus a bracketed 20-char capture name, at the toolbar font's
-    // generous ~7 px/char estimate: 38 * 7.
+    // "ReaSampler 9000" (15 chars) plus a bracketed 20-char capture name, at an assumed 7 px/char
+    // for the toolbar font: 38 * 7. A HEURISTIC, not a measured Segoe UI metric — no font-metric
+    // measurement backs this number; it gates a phase-wide acceptance criterion regardless.
     constexpr int kTitleTextFloorPx = 266;
     CHECK(r.title.width >= kTitleTextFloorPx);
     // Nothing in the run reaches into the title's slot.