Meter: proper clipping indicators

- Dedicated clip LED at the hot end (default on): lights when the
  signal reaches clipThreshold (default max), holds for clipHold ms or
  latches until clicked ('latch'); clipColor, onClip callback,
  data-clipped root attribute, data-part=clip for CSS
- clipValue prop: separate signal for clip detection so the bar can
  show RMS while the LED watches sample peaks, like real meters
- Synth: analyser loop now computes sample peaks alongside RMS and
  feeds them to the clip detector - overdriving the synth genuinely
  trips the LED
- Gallery meter demo throws occasional hot transients to exercise it;
  API docs and README updated

packages/dreamknob/README.md

@@ -96,7 +96,7 @@ import {
   Fader,        // linear channel fader, vertical or horizontal
   LEDFader,     // segmented LED meter-fader with color zones
   ImageKnob,    // film-strip sprite knob (KnobMan-style PNG strips)
-  Meter,        // read-only LED level meter with peak hold
+  Meter,        // read-only LED level meter with peak hold + latching clip LED
   XYPad,        // two-parameter pad (cutoff/resonance, vector mixing)
   PushButton,   // panel button with LED strip (toggle or momentary)
   SegmentDisplay, // standalone seven-segment numeric display