feat(BlockEditor): add minHeight prop to control minimum container height

- accept `minHeight` as number (converted to px) or css string value
- apply inline style on container when prop is defined
- document new prop in README

src/shared/components/BlockEditor/BlockEditor.client.js

@@ -69,6 +69,7 @@ export default function BlockEditor({
   disabled = false,
   className = '',
   enabledBlocks,
+  minHeight,
 }) {
   const blocks = useMemo(() => ensureNonEmpty(value), [value]);
   const blockRefs = useRef(new Map());
@@ -1014,6 +1015,7 @@ export default function BlockEditor({
         ref={containerRef}
         onKeyDown={handleGlobalKeyDown}
         onMouseDownCapture={handleContainerMouseDown}
+        style={minHeight != null ? { minHeight: typeof minHeight === 'number' ? `${minHeight}px` : minHeight } : undefined}
         className={`block-editor border rounded-xl bg-white dark:bg-neutral-900/60 px-3 py-6 ${error ? 'border-red-500/50' : 'border-neutral-300 dark:border-neutral-700/50'} ${blocks.length === 1 && inlineLength(blocks[0].content ?? []) === 0 ? 'block-editor--sole-empty' : ''} ${className}`}
       >
         <BlockEditorStyles />

src/shared/components/BlockEditor/README.md

@@ -93,6 +93,7 @@ Tous les helpers sont **purs** : ils retournent un nouveau tableau normalisé
   onChange={setBlocks}       // (Block[]) => void
   label, error, placeholder, disabled, className
   enabledBlocks={[...]}      // optionnel : restreindre les types disponibles
+  minHeight={240}            // optionnel : hauteur minimum du conteneur (number = px, ou string CSS ex. '12rem')
 />
 ```