feat(mq_editor): movable inner bezier control points + clamp() refactor

- P1/P2 in amp editor now draggable horizontally; t0<t1<t2<t3 enforced
- Add clamp() to utils.js; replace all Math.max/min clamping patterns
- Cursor hints: move for P1/P2, ns-resize for P0/P3
- Remove test_fft.html
- Docs: Delete key, style.css/utils.js in architecture, bezier editor section

handoff(Claude): inner control points done, clamp() adopted everywhere

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

1 files changed, 4 insertions, 4 deletions

diff --git a/tools/mq_editor/mq_synth.js b/tools/mq_editor/mq_synth.js
index 00867a9..a9f387c 100644
--- a/tools/mq_editor/mq_synth.js
+++ b/tools/mq_editor/mq_synth.js
@@ -42,8 +42,8 @@ function synthesizeMQ(partials, sampleRate, duration, integratePhase = true, opt
       // r controls pole radius (bandwidth): r→1 = narrow, r→0 = wide.
       // gainNorm = sqrt(1 - r²) normalises steady-state output power to ~A.
       const res      = partial.resonator || {};
-      const r        = options.forceRGain ? Math.min(0.9999, Math.max(0, options.globalR))
-                     : (res.r        != null ? Math.min(0.9999, Math.max(0, res.r)) : 0.995);
+      const r        = options.forceRGain ? clamp(options.globalR, 0, 0.9999)
+                     : (res.r        != null ? clamp(res.r, 0, 0.9999) : 0.995);
       const gainComp = options.forceRGain ? options.globalGain
                      : (res.gainComp != null ? res.gainComp : 1.0);
       const gainNorm = Math.sqrt(Math.max(0, 1.0 - r * r));
@@ -131,7 +131,7 @@ function synthesizeMQ(partials, sampleRate, duration, integratePhase = true, opt
   // LP: y[n] = k1*x[n] + (1-k1)*y[n-1]  — options.k1 in (0,1], omit to bypass
   // HP: y[n] = k2*(y[n-1] + x[n] - x[n-1]) — options.k2 in (0,1], omit to bypass
   if (options.k1 != null) {
-    const k1 = Math.max(0, Math.min(1, options.k1));
+    const k1 = clamp(options.k1, 0, 1);
     let y = 0.0;
     for (let i = 0; i < numSamples; ++i) {
       y = k1 * pcm[i] + (1.0 - k1) * y;
@@ -139,7 +139,7 @@ function synthesizeMQ(partials, sampleRate, duration, integratePhase = true, opt
     }
   }
   if (options.k2 != null) {
-    const k2 = Math.max(0, Math.min(1, options.k2));
+    const k2 = clamp(options.k2, 0, 1);
     let y = 0.0, xp = 0.0;
     for (let i = 0; i < numSamples; ++i) {
       const x = pcm[i];