feat(mq_editor): switch curve interpolation to Lagrange through all control points

Replace cubic Bezier with Lagrange interpolation so P1/P2 are actual
points on the curve. Eval uses stored t1/t2 as arbitrary knot positions.
fitBezier keeps least-squares but with Lagrange basis at u=1/3,2/3.
Remove endpoint companion drag (no longer tangent handles).
TODO: support arbitrary number of inner control points.

handoff(Claude): Lagrange interpolation replaces Bezier in mq_editor curve eval/fit.

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

1 files changed, 1 insertions, 12 deletions

diff --git a/tools/mq_editor/viewer.js b/tools/mq_editor/viewer.js
index c69d9e7..d7b5ac1 100644
--- a/tools/mq_editor/viewer.js
+++ b/tools/mq_editor/viewer.js
@@ -626,14 +626,8 @@ class SpectrogramViewer {
       if (this.selectedPartial >= 0 && this.selectedPartial < this.partials.length) {
         const ptIdx = this.hitTestControlPoint(x, y, this.partials[this.selectedPartial]);
         if (ptIdx >= 0) {
-          const curve = this.partials[this.selectedPartial].freqCurve;
-          let companionOff = null;
-          if (ptIdx === 0)
-            companionOff = { dt: curve.t1 - curve.t0, dv: curve.v1 - curve.v0 };
-          else if (ptIdx === 3)
-            companionOff = { dt: curve.t2 - curve.t3, dv: curve.v2 - curve.v3 };
           if (this.onBeforeChange) this.onBeforeChange();
-          this.dragState = { pointIndex: ptIdx, companionOff };
+          this.dragState = { pointIndex: ptIdx };
           canvas.style.cursor = 'grabbing';
           e.preventDefault();
           return;
@@ -655,11 +649,6 @@ class SpectrogramViewer {
         const i = this.dragState.pointIndex;
         partial.freqCurve['t' + i] = t;
         partial.freqCurve['v' + i] = v;
-        if (this.dragState.companionOff) {
-          const off = this.dragState.companionOff;
-          if (i === 0) { partial.freqCurve.t1 = t + off.dt; partial.freqCurve.v1 = v + off.dv; }
-          else          { partial.freqCurve.t2 = t + off.dt; partial.freqCurve.v2 = v + off.dv; }
-        }
         this.render();
         e.preventDefault();
         return;