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.

src/core/instrument/ui/loop_marks.cpp

@@ -45,8 +45,16 @@ LoopWrite applyLoopMarks(const LoopMarks& m) {
     LoopWrite w;
     const bool spanAlive = m.loopEnd > m.loopStart;
     w.loop.hasLoop = m.hasLoop && spanAlive;
-    w.loop.start = m.loopStart;
-    w.loop.end = m.loopEnd;
+    if (m.parked && !m.hasLoop) {
+        // A parked pair (never set) must round-trip back to parked, not to a real "LOOP OFF"
+        // span — resolveLoopMarks only re-parks a span spanUsable would refuse, so collapse it
+        // deliberately rather than writing back the default bounds' own alive span.
+        w.loop.start = m.loopStart;
+        w.loop.end = m.loopStart;
+    } else {
+        w.loop.start = m.loopStart;
+        w.loop.end = m.loopEnd;
+    }
     w.crossfade = (spanAlive && m.crossfade > 0) ? m.crossfade : 0;
     w.start = m.start;
     return w;

src/core/ui/theme.h

@@ -104,6 +104,14 @@ inline constexpr double kLoopSpanFillAlpha = 0.20;
 // body floor Font::Micro answers to.
 inline constexpr double kCardNameScrimAlpha = 0.75;
 
+// The waveform mark caption/label scrim: bg/base composited at this alpha UNDER the loop-state
+// caption and the four mark labels, so text/dim (Font::Micro, body class) stays readable when
+// the envelope's accent/primary peak reaches into the label's rect. Higher than
+// kCardNameScrimAlpha because text/dim needs more cover than text/primary to clear the same
+// 4.5:1 body floor against the same lime worst case — test_theme.cpp composes this exact value
+// against accent/primary to pin the floor both roles answer to.
+inline constexpr double kWaveformLabelScrimAlpha = 0.90;
+
 // Relative luminance per WCAG 2.1 (sRGB linearization + 0.2126/0.7152/0.0722 weighting). Alpha
 // is ignored — a translucent overlay's effective color is the caller's to compose first
 // (compositeOver).