feat(mq_editor): tabbed freq/amp/synth panel, spread band viz, UI polish

- Freq/Amp curve params now in tabs to save vertical space
- Add Synth tab: per-partial decay, jitter, spread_above/below controls
- Visualize spread band on selected partial (filled band + dashed bounds)
- Larger fonts and right panel (14px body, 260px panel width)
- Non-kept partials at 0.12 alpha (was 0.5)
- Default threshold -20dB (was -60dB)

handoff(Claude): mq_editor UI/UX improvements

1 files changed, 35 insertions, 0 deletions

diff --git a/tools/mq_editor/editor.js b/tools/mq_editor/editor.js
index e1e70c6..441f787 100644
--- a/tools/mq_editor/editor.js
+++ b/tools/mq_editor/editor.js
@@ -11,6 +11,7 @@ class PartialEditor {
     this._ampTitle  = document.getElementById('ampEditTitle');
     this._freqGrid  = document.getElementById('freqCurveGrid');
     this._ampGrid   = document.getElementById('ampCurveGrid');
+    this._synthGrid = document.getElementById('synthGrid');
     this._ampCtx    = this._ampCanvas ? this._ampCanvas.getContext('2d') : null;
 
     // References set by host
@@ -82,6 +83,7 @@ class PartialEditor {
 
     this._buildCurveGrid(this._freqGrid, partial, 'freqCurve', 'f', index);
     this._buildCurveGrid(this._ampGrid,  partial, 'ampCurve',  'a', index);
+    this._buildSynthGrid(partial, index);
   }
 
   _buildCurveGrid(grid, partial, curveKey, valueLabel, partialIndex) {
@@ -113,6 +115,39 @@ class PartialEditor {
     }
   }
 
+  _buildSynthGrid(partial, index) {
+    const grid = this._synthGrid;
+    grid.innerHTML = '';
+    const defaults = { decay_alpha: 0.1, jitter: 0.05, spread_above: 0.02, spread_below: 0.02 };
+    const rep = partial.replicas || {};
+    const params = [
+      { key: 'decay_alpha',  label: 'decay',    step: '0.001' },
+      { key: 'jitter',       label: 'jitter',   step: '0.001' },
+      { key: 'spread_above', label: 'spread ↑', step: '0.001' },
+      { key: 'spread_below', label: 'spread ↓', step: '0.001' },
+    ];
+    for (const p of params) {
+      const val = rep[p.key] != null ? rep[p.key] : defaults[p.key];
+      const lbl = document.createElement('span');
+      lbl.textContent = p.label;
+      const inp = document.createElement('input');
+      inp.type  = 'number';
+      inp.value = val.toFixed(3);
+      inp.step  = p.step;
+      inp.min   = '0';
+      inp.addEventListener('change', (e) => {
+        if (!this.partials) return;
+        const v = parseFloat(e.target.value);
+        if (isNaN(v)) return;
+        if (!this.partials[index].replicas)
+          this.partials[index].replicas = { ...defaults };
+        this.partials[index].replicas[p.key] = v;
+      });
+      grid.appendChild(lbl);
+      grid.appendChild(inp);
+    }
+  }
+
   _makeCurveUpdater(partialIndex, curveKey, field, pointIndex) {
     return (e) => {
       if (!this.partials) return;