type: voice, Requirement.value, playable resource cards

A voice requirement records in the browser and ships PCM to the relay
as one binary frame (voice.js, same mount/stop contract as gesture);
its value becomes {key, digest, duration_ms}. Requirement.value
presets a field and, on a dynamic page, takes the URL segment - so
value: "{key}" tells the voice field where to record. A url resource
source takes the segment too. Resource items with an https `audio`
field render an <audio> player. The gesture widget reports picks to
the relay for ranking.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

style/main.css

@@ -448,6 +448,57 @@ main.not-found {
   margin-bottom: 0.15em;
 }
 
+/* voice field (voice.js): a record button, a status line, a preview */
+.voice-wrap {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 0.6rem 1rem;
+}
+
+.voice-button {
+  font: inherit;
+  padding: 0.55rem 1.1rem;
+  border: 0.06rem solid var(--accent);
+  border-radius: 2rem;
+  background: transparent;
+  color: var(--ink);
+  cursor: pointer;
+}
+
+.voice-button:hover:not(:disabled) {
+  background: var(--accent);
+  color: var(--paper);
+}
+
+.voice-button.recording {
+  background: var(--accent);
+  color: var(--paper);
+  animation: voice-pulse 1.2s ease-in-out infinite;
+}
+
+.voice-button:disabled {
+  opacity: 0.5;
+  cursor: default;
+}
+
+@keyframes voice-pulse {
+  50% { opacity: 0.6; }
+}
+
+.voice-status {
+  font-size: 0.85rem;
+  color: var(--ink-dim);
+}
+
+.voice-preview,
+.item-card-audio {
+  display: block;
+  width: 100%;
+  max-width: 28rem;
+  margin-top: 0.4rem;
+}
+
 /* links inside markdown descriptions */
 .alt-description a,
 .feature p a {