fix: wire positions on zoom, MIDI import, envelope release min

- Fix wires not recalculating positions on zoom until panning
- Add MIDI file import button to Piano Roll (parses .mid files)
- Allow envelope release to go to 0 (was clamped at 0.001)

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

src/components/PianoRollWidget.jsx

@@ -2,6 +2,7 @@ import React, { useState, useEffect, useRef, useCallback } from 'react';
 import * as Tone from 'tone';
 import { state, updateModuleParam, emit } from '../engine/state.js';
 import { setSequencerSignals } from '../engine/audioEngine.js';
+import { parseMidi } from '../utils/midiParser.js';
 
 const NOTE_NAMES = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B'];
 const BLACK_KEYS = [1, 3, 6, 8, 10];
@@ -65,6 +66,7 @@ export default function PianoRollWidget({ moduleId }) {
   const [tool, setTool] = useState('draw'); // 'draw' | 'erase'
   const drawingRef = useRef(null);
   const rafRef = useRef(null);
+  const midiInputRef = useRef(null);
 
   const bpm = mod?.params?.bpm ?? 140;
   const bars = parseInt(mod?.params?.bars || '4');
@@ -321,6 +323,37 @@ export default function PianoRollWidget({ moduleId }) {
     }
   }, [tool, notes, beatW, totalBeats, mod]);
 
+  const handleMidiImport = useCallback(async (e) => {
+    const file = e.target.files[0];
+    if (!file) return;
+    try {
+      const arrayBuffer = await file.arrayBuffer();
+      const midi = parseMidi(arrayBuffer);
+      if (midi.notes.length === 0) return;
+
+      // Update BPM if detected
+      if (midi.bpm && mod) {
+        mod.params.bpm = midi.bpm;
+      }
+
+      // Auto-fit bars to cover all notes
+      const maxBeat = Math.max(...midi.notes.map(n => n.start + n.duration));
+      const neededBars = Math.ceil(maxBeat / 4);
+      const fitBars = [1, 2, 4, 8].find(b => b >= neededBars) || 8;
+      if (mod) mod.params.bars = String(fitBars);
+
+      // Set notes
+      if (mod) {
+        mod.params._notes = midi.notes;
+        notesRef.current = midi.notes;
+        emit();
+      }
+    } catch (err) {
+      console.error('[PianoRoll] MIDI import failed:', err);
+    }
+    e.target.value = '';
+  }, [mod]);
+
   return (
     <div style={{ width: ROLL_W }}>
       {/* Mini toolbar */}
@@ -345,6 +378,15 @@ export default function PianoRollWidget({ moduleId }) {
           }}
           onClick={() => setTool('erase')}
         >✕ Erase</button>
+        <button
+          style={{
+            padding: '1px 6px', fontSize: 9, border: '1px solid #333',
+            background: '#111', color: '#888',
+            borderRadius: 3, cursor: 'pointer', fontFamily: 'inherit',
+          }}
+          onClick={() => midiInputRef.current?.click()}
+        >🎵 MIDI</button>
+        <input ref={midiInputRef} type="file" accept=".mid,.midi" style={{ display: 'none' }} onChange={handleMidiImport} />
         <span style={{ fontSize: 8, color: '#555', marginLeft: 'auto', alignSelf: 'center' }}>
           {notes.length} notes · {bars} bars
         </span>