Add audio capture timing metrics to target pipeline

Instrument AudioCaptureStream with read/FFT timing and
AudioColorStripStream with render timing. Display audio-specific
timing segments (read/fft/render/send) in the target card
breakdown bar when an audio source is active.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/css/cards.css

@@ -553,6 +553,9 @@ ul.section-tip li {
 .timing-map { background: #FF9800; }
 .timing-smooth { background: #2196F3; }
 .timing-send { background: #E91E63; }
+.timing-audio-read { background: #4CAF50; }
+.timing-audio-fft { background: #FF9800; }
+.timing-audio-render { background: #2196F3; }
 
 .timing-legend {
     display: flex;
@@ -580,6 +583,9 @@ ul.section-tip li {
 .timing-dot.timing-map { background: #FF9800; }
 .timing-dot.timing-smooth { background: #2196F3; }
 .timing-dot.timing-send { background: #E91E63; }
+.timing-dot.timing-audio-read { background: #4CAF50; }
+.timing-dot.timing-audio-fft { background: #FF9800; }
+.timing-dot.timing-audio-render { background: #2196F3; }
 
 @media (max-width: 768px) {
     .displays-grid,