fix(BlockEditor): constrain select-all to current block and resize slash menu

- intercept Ctrl/Cmd+A to select only the current block's content, preventing cross-block merge bug
- increase slash menu width from 280 to 375 and max-height from 320 to 360
- enlarge icon container, increase gap and padding, and upsize text in slash menu items

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

@@ -120,6 +120,21 @@ const Block = forwardRef(function Block(
       return;
     }
 
+    // Ctrl/Cmd+A : limite la sélection au bloc courant. La sélection native
+    // s'étend sur plusieurs contentEditable et leur suppression fusionne le
+    // texte en un seul bloc — bug. On force la sélection à rester ici.
+    if ((e.ctrlKey || e.metaKey) && (e.key === 'a' || e.key === 'A')) {
+      if (el) {
+        e.preventDefault();
+        const range = document.createRange();
+        range.selectNodeContents(el);
+        const sel = window.getSelection();
+        sel?.removeAllRanges();
+        sel?.addRange(range);
+      }
+      return;
+    }
+
     if (e.key === 'Enter' && !e.shiftKey) {
       e.preventDefault();
       const el = editableRef.current;

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

@@ -2,8 +2,8 @@
 
 import React, { useEffect, useLayoutEffect, useMemo, useRef, useState } from 'react';
 
-const MENU_WIDTH = 280;
+const MENU_WIDTH = 375;
-const MENU_MAX_HEIGHT = 320;
+const MENU_MAX_HEIGHT = 360;
 const VIEWPORT_MARGIN = 8;
 
 const SHORTCUT_HINT = {
@@ -135,16 +135,16 @@ export default function SlashMenu({
             data-slash-index={i}
             onMouseEnter={() => onHoverIndex?.(i)}
             onClick={() => onSelect?.(def.type)}
-            className={`w-full flex items-center gap-2.5 px-2 py-1 text-left transition-colors ${active ? 'bg-neutral-100 dark:bg-neutral-800' : ''}`}
+            className={`w-full flex items-center gap-3 px-2 py-1.5 text-left transition-colors ${active ? 'bg-neutral-100 dark:bg-neutral-800' : ''}`}
           >
-            <span className="w-6 h-6 flex items-center justify-center rounded-[5px] border border-neutral-200 dark:border-neutral-700 text-[11px] font-medium text-neutral-700 dark:text-neutral-300 flex-shrink-0">
+            <span className="w-8 h-8 flex items-center justify-center rounded-md border border-neutral-200 dark:border-neutral-700 text-xs font-medium text-neutral-700 dark:text-neutral-300 flex-shrink-0">
               {def.icon}
             </span>
-            <span className="flex-1 min-w-0 truncate text-[13px] text-neutral-900 dark:text-white">
+            <span className="flex-1 min-w-0 truncate text-sm text-neutral-900 dark:text-white">
               {def.label}
             </span>
             {hint && (
-              <span className="text-[11px] font-mono text-neutral-400 dark:text-neutral-500 flex-shrink-0">
+              <span className="text-xs font-mono text-neutral-400 dark:text-neutral-500 flex-shrink-0">
                 {hint}
               </span>
             )}