fix(escuchar,reproductor): add the section-heading token and screen 1-3 polish

Audit S7 plus the open items on screens 1-3. Escuchar gains the
prototype's own 52px "now listening" eyebrow header (t4:53), which is
structurally different from the 56px title row every other root uses
(t4:325) -- the earlier wiring test asserted PluriRootHeader on all five
roots, an over-broad premise now corrected to guard what actually holds:
no AppBar, and the sleep-timer action still reachable.

test/tema/pluriwave_typography_test.dart

@@ -65,6 +65,20 @@ void main() {
       expect(type.eyebrowLabel.letterSpacing, 0.8);
     });
 
+    test(
+      'S7 (visual fidelity): inPageSectionHeading is 15 / w800 / '
+      'letter-spacing -0.2 -- the ADR-1 amendment adding a seventh style',
+      () {
+        expect(
+          type.inPageSectionHeading.fontSize,
+          15,
+          reason: 'prototype t4 lines 80, 153, 164, 173',
+        );
+        expect(type.inPageSectionHeading.fontWeight, FontWeight.w800);
+        expect(type.inPageSectionHeading.letterSpacing, -0.2);
+      },
+    );
+
     test('S9 (Tier 1 visual fidelity): eyebrowLabel bakes in the prototype '
         "colour rgba(242,247,250,.42) — it used to carry no colour at all, "
         'so it rendered at full onSurface opacity', () {