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

apps/docs/src/App.tsx

@@ -1,9 +1,12 @@
 import React from 'react';
+import { AdvancedGuide } from './sections/AdvancedGuide';
 import { ApiDocs } from './sections/ApiDocs';
 import { Console } from './sections/Console';
 import { Gallery } from './sections/Gallery';
+import { GettingStarted } from './sections/GettingStarted';
 import { Hero } from './sections/Hero';
 import { Playground } from './sections/Playground';
+import { Synth } from './sections/Synth';
 
 const Logo: React.FC = () => (
   <svg width="22" height="22" viewBox="0 0 100 100">
@@ -21,17 +24,22 @@ export const App: React.FC = () => (
           dreamknob
         </a>
         <div className="nav-links">
+          <a href="#start">Start</a>
           <a href="#gallery">Gallery</a>
-          <a href="#console">Demo</a>
+          <a href="#synth">Synth</a>
           <a href="#playground">Playground</a>
+          <a href="#guide">Guide</a>
           <a href="#docs">Docs</a>
         </div>
       </div>
     </nav>
     <Hero />
+    <GettingStarted />
     <Gallery />
     <Console />
+    <Synth />
     <Playground />
+    <AdvancedGuide />
     <ApiDocs />
     <footer className="footer">
       <div className="container">