Plate docs examples should use PlateContent under Plate

Problem

A docs example tried to mirror Slate by rendering a raw Editable inside <Plate>. That crashed at runtime even though the page shape looked valid.

Symptoms

• The browser threw The useSlate hook must be used inside the <Slate> component's context.
• The stack pointed at the Plate pane's Editable.
• The same page could still render the Slate pane, which made the failure look like a data or render-prop issue when it was really the wrong wrapper.

What Didn't Work

Using the same raw Editable component in both panes looked clean, but Plate is not just "Slate plus more props". The Plate side needs the wrapper that installs Plate's editable pipeline and Slate context in the right order.

Solution

Render PlateContent under <Plate> instead of raw Editable.

Before:

<Plate editor={editor as any}>
  <Editable
    placeholder="Enter some text…"
    renderChunk={config.chunkDivs ? (renderChunk as any) : undefined}
    renderElement={renderElement as any}
    spellCheck
  />
</Plate>

After:

<Plate editor={editor as any}>
  <PlateContent
    placeholder="Enter some text…"
    renderChunk={config.chunkDivs ? (renderChunk as any) : undefined}
    renderElement={renderElement as any}
    spellCheck
  />
</Plate>

Why This Works

PlateContent is the Plate-owned editable surface. It installs PlateSlate, useEditableProps, effect wiring, and the rest of the editable stack before rendering the underlying Slate editable. Raw Editable skips that setup, so hooks like useSlate run without the context they expect.

Prevention

• In docs examples, use raw Editable only for pure Slate examples.
• In Plate examples, prefer PlateContent or the repo's Editor wrapper from editor.tsx.
• If a Plate example throws a Slate-context hook error, check the editable wrapper before chasing render props or node types.