Tier 1: origin anchor, detents, theming, type-in editing, ImageKnob

- origin: bipolar anchor value — Arc from=center, Fader fill and
  LEDFader segments draw from origin instead of min/mid-travel
- detents + detentSize: magnetic snap while dragging (normalized
  space, wheel/keyboard unaffected); applyDetents exported
- DreamknobProvider + KnobTheme: accent/track/face/text/label/ticks/
  focusRing/fonts tokens with dark and light bases; every skin
  resolves defaults from the theme, instance props win
- editable + parseValue: double-click knobs (or click fader readouts)
  to type exact values; Enter/blur commits, Esc cancels, 1.2k parses;
  ValueInput + defaultParseValue exported; setValue added to context
- ImageKnob: film-strip sprite knob (KnobMan-style strips), vertical
  or horizontal, with focus ring, editing, value/label
- Docs: LED gallery cards for film-strip/bipolar/editing/theming,
  playground editable toggle, theming API section, README updates

packages/dreamknob/src/skins/shared.ts

@@ -1,6 +1,8 @@
 import type * as React from 'react';
 import type { KnobCoreProps } from '../core/types';
 
+export { MONO_FONT, UI_FONT } from '../core/theme';
+
 /** Props common to every prebuilt knob skin. */
 export interface SkinProps extends KnobCoreProps {
   /** Square canvas size in px. */
@@ -13,11 +15,15 @@ export interface SkinProps extends KnobCoreProps {
   unit?: string;
   /** Custom readout formatter (takes precedence over unit/decimals). */
   format?: (value: number) => string;
+  /** Keyboard focus ring color, or false to disable. Defaults to the theme's. */
+  focusRing?: string | false;
+  /**
+   * Type-in editing: double-click (knobs) or click the readout (faders) to
+   * enter an exact value. Enter/blur commits, Escape cancels, "1.2k" works.
+   */
+  editable?: boolean;
+  /** Custom parser for typed input when `editable` is set. */
+  parseValue?: (text: string) => number | null;
   className?: string;
   style?: React.CSSProperties;
 }
-
-export const MONO_FONT =
-  "'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace";
-export const UI_FONT =
-  "'Inter', ui-sans-serif, system-ui, -apple-system, 'Segoe UI', sans-serif";