fix(pe-guide): remove PVC entry from cardiac sounds library

PVCs are an ECG / rhythm finding, not a routine auscultation sample —
what you actually hear on the stethoscope is an irregular rhythm with a
compensatory pause, which depends on the underlying rate and is not
teachable from a canned audio clip. The card was also backed by a
synthesized sound, not a real recording. Removing both the card and
the pvc.ogg asset.

public/js/peGuide.js

@@ -307,11 +307,7 @@
     { key: 'functional', src: '/audio/cardiac/functional-murmur.wav', title: 'Functional (innocent) murmur — adult female',
       where: 'Left sternal border, soft systolic',
       features: 'Soft systolic murmur in a structurally normal heart — often from increased cardiac output, thin chest wall, anemia, hyperthyroidism, or pregnancy.',
-      clinical: 'Benign if it meets the 7 S criteria. Investigate if loud (≥3/6), holosystolic, diastolic, radiating, or with thrill / symptoms.' },
-    { key: 'pvc', src: '/audio/cardiac/pvc.ogg', title: 'Premature ventricular contractions (PVCs)',
-      where: 'Apex; detect via irregular rhythm',
-      features: 'Irregular rhythm with a compensatory pause after the early beat. Pulse may be irregular on palpation.',
-      clinical: 'Common and usually benign in structurally normal hearts. Investigate if frequent (>10/min), symptomatic (syncope), or with exertional worsening. Workup: ECG, ambulatory monitor, consider echo.' }
+      clinical: 'Benign if it meets the 7 S criteria. Investigate if loud (≥3/6), holosystolic, diastolic, radiating, or with thrill / symptoms.' }
   ];
 
   // ────────────────────────────────────────────────────────────