fix: LFO→cutoff modulation, visual knob feedback, persistent hints

- Fix LFO→Filter cutoff: add scaling Gain nodes so LFO (-1..1) maps to
  meaningful Hz modulation (±cutoff value). Same fix for LFO→Osc freq.
  Mod scale updates dynamically when user changes the base param value.
- Visual modulation indicator: knobs receiving LFO/modulation show a
  pulsing dashed ring animation (spin + pulse) around the knob arc
- Persist hint usage per level: using a hint permanently caps that level
  at 2 stars — survives reload/restart. No more cheating by restarting!
- Hint state stored in separate localStorage key (synthquest-hints)
- Admin reset also clears hint history

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

src/components/ModuleNode.jsx

@@ -8,6 +8,13 @@ import KeyboardWidget from './KeyboardWidget.jsx';
 import SequencerWidget from './SequencerWidget.jsx';
 import PianoRollWidget from './PianoRollWidget.jsx';
 
+// Map input port names → the param name they modulate (for visual feedback)
+const PORT_TO_PARAM = {
+  filter:     { cutoff: 'frequency' },
+  oscillator: { freq: 'frequency', detune: 'detune' },
+  vca:        { cv: 'gain' },
+};
+
 export default function ModuleNode({ mod, zoom, onStartConnect, onPortPosition }) {
   const def = getModuleDef(mod.type);
   if (!def) return null;
@@ -17,6 +24,15 @@ export default function ModuleNode({ mod, zoom, onStartConnect, onPortPosition }
   // Merge default params
   const params = { ...Object.fromEntries(Object.entries(def.params).map(([k, v]) => [k, v.default])), ...mod.params };
 
+  // Find which params are being modulated (have an incoming connection on their corresponding port)
+  const modulatedParams = new Set();
+  const portMap = PORT_TO_PARAM[mod.type] || {};
+  for (const conn of state.connections) {
+    if (conn.to.moduleId === mod.id && portMap[conn.to.port]) {
+      modulatedParams.add(portMap[conn.to.port]);
+    }
+  }
+
   const handleParamChange = useCallback((name, value) => {
     updateModuleParam(mod.id, name, value);
     updateParam(mod.id, name, value);
@@ -117,6 +133,7 @@ export default function ModuleNode({ mod, zoom, onStartConnect, onPortPosition }
                   max={paramDef.max}
                   onChange={v => handleParamChange(name, v)}
                   color={color}
+                  modulated={modulatedParams.has(name)}
                 />
                 <span className="param-value">
                   {params[name] >= 1000 ? `${(params[name] / 1000).toFixed(1)}k` :