fix: allow dragging all gates + stop waveform recording on edits

- INPUT/CLOCK gates can now be dragged (click-without-move = toggle,
  click-and-drag = move). Uses 4px movement threshold.
- Waveform only records samples on intentional actions (INPUT toggle,
  manual step, simulation tick), not on gate placement/movement/connections.

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

js/gates.js

@@ -53,12 +53,12 @@ export function evaluate(gate, visited = new Set()) {
     return result;
 }
 
-export function evaluateAll() {
+export function evaluateAll(recordWave = false) {
     state.gates.forEach(g => {
         if (g.type !== 'INPUT' && g.type !== 'CLOCK') g.value = 0;
     });
     state.gates.forEach(g => evaluate(g));
-    if (state.recording && state.waveformVisible) recordSample();
+    if (recordWave && state.recording && state.waveformVisible) recordSample();
 }
 
 // Register evaluateAll in waveform to break circular dependency