feat(tts): integrate autonomous Piper neural TTS with zero-latency pre-warming for words and context

app/static/css/style.css

@@ -905,6 +905,37 @@ body.drawer-open {
     color: #0f172a;
 }
 
+.audio-xs-btn {
+    background-color: var(--primary-dim);
+    border: 1px solid var(--primary);
+    color: var(--primary);
+    border-radius: var(--radius-full);
+    padding: 2px 8px;
+    font-size: 11px;
+    font-weight: 600;
+    cursor: pointer;
+    display: inline-flex;
+    align-items: center;
+    gap: 4px;
+    transition: var(--transition);
+}
+
+.audio-xs-btn:hover {
+    background-color: var(--primary);
+    color: #0f172a;
+}
+
+.popup-sentence-audio-btn {
+    border-color: var(--border-color);
+    color: var(--text-muted);
+}
+
+.popup-sentence-audio-btn:hover {
+    border-color: var(--primary);
+    color: var(--primary);
+    background-color: var(--primary-dim);
+}
+
 .definition-box {
     background-color: var(--bg-main);
     border-left: 3px solid var(--primary);