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_theme.cpp

@@ -269,6 +269,25 @@ static void testCardNameScrimClearsBodyFloorOnItsWorstBackground() {
           < textFloor(TextClass::Body));
 }
 
+// The waveform band's state caption and its four mark labels (editor_paint_waveform.cpp) draw
+// text/dim (the caption, the non-promoted labels) and text/primary (the promoted label) — both
+// Font::Micro, both body class — over a bg/base scrim at kWaveformLabelScrimAlpha, itself drawn
+// over whatever drawEnvelope left in that rect. Unlike the card name strip, the worst case here
+// is text/DIM, not text/primary, so the alpha is higher than kCardNameScrimAlpha's — pin both
+// roles against the worst background (a full-scale envelope peak, accent/primary) and pin the
+// defect the scrim exists to close.
+static void testWaveformLabelScrimClearsBodyFloorOnItsWorstBackground() {
+    const KitColor scrim = roleColor(Role::BgBase);
+    const KitColor onFill = compositeOver(scrim, roleColor(Role::AccentPrimary),
+                                          kWaveformLabelScrimAlpha);
+    CHECK(contrastRatio(roleColor(Role::TextDim), onFill) >= textFloor(TextClass::Body));
+    CHECK(contrastRatio(roleColor(Role::TextPrimary), onFill) >= textFloor(TextClass::Body));
+    // Without the scrim, text/dim on the bare accent-lime fill is UNDER floor (~1.58:1) — pins
+    // the defect the scrim exists to close, so a future removal of the scrim fails this first.
+    CHECK(contrastRatio(roleColor(Role::TextDim), roleColor(Role::AccentPrimary))
+          < textFloor(TextClass::Body));
+}
+
 // --- Single point of change (structural guarantee) ----------------------------
 //
 // roleColor is the ONLY color source; there is no other public accessor that yields a
@@ -366,6 +385,7 @@ int main() {
     testTextOnPastelFillClearsBodyFloor();
     testTextOnHoverSurfaceClearsFloor();
     testCardNameScrimClearsBodyFloorOnItsWorstBackground();
+    testWaveformLabelScrimClearsBodyFloorOnItsWorstBackground();
     testCurveTraceOnHoverSurfaceClearsFloor();
     testSecondaryTertiaryAreDistinguishable();
     testOverlayTraceClearsIndicatorFloorOnTheWaveform();