Docs accuracy pass, guides, and a playable Web Audio synth demo

Docs/playground accuracy (from a full docs-vs-source audit):
- Playground: drag-feel select covers pickup/relative rotary modes, is
  disabled for faders, and generated code no longer emits props the
  target component does not accept
- API/README claims corrected: Shift-fine wheel scope, wheelStep and
  decimals defaults, trackInset row, data-part and ref-forwarding
  scope, VintageKnob readout exception, Meter peakHold tag, stale
  component lists, aria-valuetext wording, also-exported list

API consistency fixes surfaced by the audit and the tutorial:
- Keyboard gestures now fire onChangeStart (bracket parity with drag/
  wheel - fixes gesture-scoped undo patterns)
- name (hidden form input) added to Fader, LEDFader, ImageKnob
- PushButton gets a themed keyboard-only focus ring + data-focus-visible

New docs content:
- Getting Started: 7-step guide with live examples and a gotchas list
- Advanced guide: 8-step channel-strip tutorial ending in a live,
  themed, gesture-undoable strip with meter (plus headless demo)
- Synth section: playable Web Audio synth - osc/filter/env/LFO/master
  all dreamknob controls, momentary-pad keyboard, analyser-driven Meter

packages/dreamknob/README.md

@@ -41,7 +41,7 @@ Every component shares one core:
 | Gesture | Behaviour |
 | --- | --- |
 | Drag | `rotary` (grab & turn, follows the pointer angle), `vertical`, `horizontal`, `both`, or absolute `track-*` (faders) |
-| Scroll wheel | one `step` per notch, `Shift` = fine |
+| Scroll wheel | one `step` per notch (else 1% of range); `Shift` = fine on continuous values — snapped controls always move whole steps |
 | `↑ → / ↓ ←` | ± one step (`Shift` = 10×) |
 | `PageUp/PageDown` | ± 10 % of range |
 | `Home/End` | min / max |
@@ -49,7 +49,8 @@ Every component shares one core:
 | `Escape` | cancel an in-flight drag, restoring the start value |
 | Touch / pen | pointer capture, `touch-action: none` |
 
-All knobs render `role="slider"` with `aria-valuemin/max/now/text`.
+All knobs render `role="slider"` with `aria-valuemin/max/now` (and `aria-valuetext`
+when you provide `getAriaValueText`).
 
 ## Value handling
 
@@ -76,8 +77,10 @@ All knobs render `role="slider"` with `aria-valuemin/max/now/text`.
 - `animateChanges` — tween the pointer on programmatic changes (preset loads);
   gestures never animate and `prefers-reduced-motion` is honored.
 - `valueBubble` — floating readout above the control while dragging.
-- `name` — hidden form input for plain `<form>` posts; every component forwards a
-  ref to its root element, and SVG parts carry `data-part` attributes for CSS.
+- `name` — hidden form input for plain `<form>` posts on every knob, fader and
+  `PushButton` (`XYPad` uses `nameX`/`nameY`). Interactive components forward a ref
+  to their root element, and primitive-drawn SVG parts carry `data-part` attributes
+  for CSS styling.
 
 ## Prebuilt skins
 
@@ -114,8 +117,17 @@ import { DreamknobProvider } from 'dreamknob'
 `base="light"` swaps in light-background defaults. Tokens: `accent`, `track`, `face`,
 `text`, `label`, `ticks`, `focusRing`, `fontMono`, `fontUI`.
 
-Every skin takes the core props plus `size`, `label`, `showValue`, `unit`, `format`,
-and per-part color props (`color`, `trackColor`, `faceColor`, `bodyColor`, …).
+Every knob skin and fader takes the core props plus `size`, `label`, `showValue`,
+`unit`, `format`, and per-part color props (`color`, `trackColor`, `faceColor`,
+`bodyColor`, …). `VintageKnob` has no readout, so it omits `showValue`/`unit`/`format`;
+the display components (`Meter`, `SegmentDisplay`, `AlphaDisplay`) have their own
+smaller prop sets.
+
+Also exported for custom builds: primitives (`Arc`, `Pointer`, `Ticks`, `TickLabels`,
+`Face`, `KnobValue`, `KnobLabel`, `GlowFilter`), theming (`useKnobTheme`, `darkTheme`,
+`lightTheme`), editing (`ValueInput`, `defaultParseValue`), colors (`mixColors`,
+`sampleGradient`), and the math kit (`clamp`, `roundTo`, `snapToStep`,
+`decimalsFromStep`, `findClosest`, `applyDetents`, tapers, angle/arc helpers).
 
 ## Compose your own