fix: use RichEditor with readOnly prop instead of raw HTML for locked/invalidated offers

RichEditor now supports readOnly prop — hides toolbar and disables
editing via ReactQuill's built-in readOnly. Content renders with
proper Quill CSS (list margins, indentation, fonts) instead of
broken browser defaults from dangerouslySetInnerHTML.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/admin/pages/OfferDetail.tsx

@@ -1097,22 +1097,13 @@ export default function OfferDetail() {
 
                   <div style={{ marginTop: '0.5rem' }}>
                     <label className="admin-form-label">Obsah</label>
-                    {(isInvalidated || isLockedByOther) ? (
-                      <div className="rich-editor">
-                        <div
-                          className="ql-editor"
-                          style={{ minHeight: '80px', background: 'var(--bg-primary)', border: '1px solid var(--border-color)', borderRadius: 'var(--border-radius-sm)', cursor: 'default', overflowWrap: 'anywhere', wordBreak: 'break-word' }}
-                          dangerouslySetInnerHTML={{ __html: section.content || '<em style="color: var(--text-tertiary)">Prázdný obsah</em>' }}
-                        />
-                      </div>
-                    ) : (
-                      <RichEditor
-                        value={section.content}
-                        onChange={(val) => setSections(prev => prev.map((s, i) => i === idx ? { ...s, content: val } : s))}
-                        placeholder="Obsah sekce..."
-                        minHeight="120px"
-                      />
-                    )}
+                    <RichEditor
+                      value={section.content}
+                      onChange={(val) => setSections(prev => prev.map((s, i) => i === idx ? { ...s, content: val } : s))}
+                      placeholder="Obsah sekce..."
+                      minHeight="120px"
+                      readOnly={isInvalidated || isLockedByOther}
+                    />
                   </div>
                 </div>
               ))}