Audit fixes: a11y, gesture correctness, math edge cases

- Keyboard focus-visible ring on all controls (WCAG 2.4.7), suppressed
  for pointer grabs; focusRing prop to customize or disable
- aria-orientation on track modes; data-dragging/-disabled/-readonly/
  -focus-visible state attributes; disabled dims, readOnly drops the
  grab cursor
- Escape cancels a drag and restores the pre-gesture value
- Controlled mode no longer desyncs when the parent rejects onChange
- Second concurrent pointer can no longer hijack a drag session;
  drags cancel when disabled/readOnly flips mid-gesture
- Wheel: onChangeStart symmetry, settle flush on unsubscribe, dominant-
  axis direction (fixes macOS Shift+scroll reversal), ignored mid-drag
- Shift+wheel and fine multipliers now work on stepped/values knobs
- Fader/LEDFader track mapping inset-aligned with handle travel (no
  value jump when grabbing the cap); LEDFader zones sorted
- roundTo no longer returns NaN for exponential-notation values;
  logTaper falls back to linear for invalid ranges; decimalsFromStep
  shaves float noise; findClosest([]) returns the input
- Double-click reset brackets with onChangeStart/End
- MetalKnob honors showValue/unit/format; VintageKnob omits them from
  its type; TickLabels extracted as a public primitive
- SegmentDisplay: letters/hex charset, dash overflow instead of 888

packages/dreamknob/src/primitives/TickLabels.tsx

@@ -0,0 +1,53 @@
+import * as React from 'react';
+import { useKnobContext } from '../core/context';
+import { polarToCartesian } from '../core/math';
+
+export interface TickLabelsProps {
+  /** Labels distributed evenly across the travel, e.g. ['0','','5','','10']. */
+  labels: readonly string[];
+  /** Radius of the label ring. Defaults to just inside the canvas edge. */
+  radius?: number;
+  fontSize?: number;
+  color?: string;
+  fontFamily?: string;
+  /** Extra props per label, by index. */
+  getLabelProps?: (index: number) => React.SVGProps<SVGTextElement> | undefined;
+}
+
+/** Printed scale labels around the knob's travel (0…10 amp-style scales). */
+export const TickLabels: React.FC<TickLabelsProps> = ({
+  labels,
+  radius,
+  fontSize,
+  color = 'currentColor',
+  fontFamily,
+  getLabelProps,
+}) => {
+  const { size, center: c, angleOffset, angleRange } = useKnobContext();
+  const r = radius ?? size / 2 - size * 0.02;
+  return (
+    <g>
+      {labels.map((text, i) => {
+        if (!text) return null;
+        const t = labels.length === 1 ? 0 : i / (labels.length - 1);
+        const p = polarToCartesian(c, c, r, angleOffset + t * angleRange);
+        return (
+          <text
+            key={i}
+            x={p.x}
+            y={p.y}
+            textAnchor="middle"
+            dominantBaseline="central"
+            fontSize={fontSize ?? size * 0.085}
+            fontFamily={fontFamily}
+            fill={color}
+            style={{ pointerEvents: 'none' }}
+            {...getLabelProps?.(i)}
+          >
+            {text}
+          </text>
+        );
+      })}
+    </g>
+  );
+};