feat(mq_editor): peaks display, STFT cache refactor, threshold reactivity

- STFTCache: cache squaredAmplitude (re²+im²) per frame, add getSquaredAmplitude(t)
- getMagnitudeDB uses cached sq amp (10*log10, no sqrt)
- detectPeaks uses squaredAmp from cache instead of recomputing FFT
- extractPartials: use cache frames, return {partials, frames}
- Press 'p' to toggle raw peak overlay in viewer
- threshold input: step=any, change event triggers re-extraction
- runExtraction() shared by button and threshold change

handoff(Claude): mq_partial peaks/cache refactor complete

1 files changed, 21 insertions, 10 deletions

diff --git a/tools/mq_editor/index.html b/tools/mq_editor/index.html
index 84abd1c..27eba2a 100644
--- a/tools/mq_editor/index.html
+++ b/tools/mq_editor/index.html
@@ -82,7 +82,7 @@
       <input type="number" id="hopSize" value="256" min="64" max="1024" step="64">
 
       <label>Threshold (dB):</label>
-      <input type="number" id="threshold" value="-60" min="-80" max="-20" step="5">
+      <input type="number" id="threshold" value="-60" step="any">
     </div>
   </div>
 
@@ -173,9 +173,8 @@
       }
     });
 
-    // Extract partials
-    extractBtn.addEventListener('click', () => {
-      if (!audioBuffer) return;
+    function runExtraction() {
+      if (!stftCache) return;
 
       setStatus('Extracting partials...', 'info');
       extractBtn.disabled = true;
@@ -189,13 +188,12 @@
             sampleRate: audioBuffer.sampleRate
           };
 
-          const partials = extractPartials(audioBuffer, params);
+          const result = extractPartials(params, stftCache);
 
-          extractedPartials = partials;
-          setStatus(`Extracted ${partials.length} partials`, 'info');
-
-          // Update viewer
-          viewer.setPartials(partials);
+          extractedPartials = result.partials;
+          viewer.setFrames(result.frames);
+          setStatus(`Extracted ${result.partials.length} partials`, 'info');
+          viewer.setPartials(result.partials);
 
         } catch (err) {
           setStatus('Extraction error: ' + err.message, 'error');
@@ -203,6 +201,16 @@
         }
         extractBtn.disabled = false;
       }, 50);
+    }
+
+    // Extract partials
+    extractBtn.addEventListener('click', () => {
+      if (!audioBuffer) return;
+      runExtraction();
+    });
+
+    threshold.addEventListener('change', () => {
+      if (stftCache) runExtraction();
     });
 
     // Play audio
@@ -325,6 +333,9 @@
         if (!playBtn.disabled) {
           playBtn.click();
         }
+      } else if (e.code === 'KeyP') {
+        e.preventDefault();
+        if (viewer) viewer.togglePeaks();
       }
     });
   </script>