fix(insights): notes markdown + equations LaTeX rendues correctement

Markdown notes:
- peekNote.isMarkdown → MarkdownContent (react-markdown + remarkMath + rehypeKatex)
- GFM tables, code blocks, etc. supportés nativement

Rich text notes:
- KaTeX CSS importé (katex.min.css)
- useEffect rend les equations data-latex via katex.renderToString
- math-equation-block → display mode
- inline-math → inline mode

KaTeX lazy-loadé (await import('katex')) — pas dans le bundle initial

memento-note/app/(main)/insights/page.tsx

@@ -29,6 +29,8 @@ import { getNoteById } from '@/app/actions/notes'
 import type { Note as NoteFull } from '@/lib/types'
 import { X, Maximize2 } from 'lucide-react'
 import DOMPurify from 'dompurify'
+import { MarkdownContent } from '@/components/markdown-content'
+import 'katex/dist/katex.min.css'
 
 const NetworkGraph = dynamic(
   () => import('@/components/network-graph').then(m => ({ default: m.NetworkGraph })),
@@ -277,6 +279,22 @@ export default function InsightsPage() {
 
   const closePeek = () => setPeekNote(null)
 
+  // Rendu KaTeX pour les notes richtext (data-latex)
+  useEffect(() => {
+    if (!peekNote || peekNote.isMarkdown) return
+    const timer = setTimeout(async () => {
+      const container = document.getElementById('insights-peek-content')
+      if (!container) return
+      const katex = (await import('katex')).default
+      container.querySelectorAll('.math-equation-block[data-latex], .inline-math[data-latex]').forEach(el => {
+        const latex = el.getAttribute('data-latex') || ''
+        const isDisplay = el.classList.contains('math-equation-block')
+        try { el.innerHTML = katex.renderToString(latex, { displayMode: isDisplay, throwOnError: false }) } catch {}
+      })
+    }, 100)
+    return () => clearTimeout(timer)
+  }, [peekNote])
+
   const openPeekFully = () => {
     if (!peekNote) return
     router.push(`/home?openNote=${peekNote.id}`)
@@ -932,7 +950,11 @@ export default function InsightsPage() {
                   {peekNote.title || t('insightsView.unknownNote')}
                 </h2>
                 {peekNote.content ? (
+                  peekNote.isMarkdown ? (
+                    <MarkdownContent content={peekNote.content} className="prose-lg" />
+                  ) : (
                   <div
+                    id="insights-peek-content"
                     dir="auto"
                     className="editor-body prose prose-lg dark:prose-invert max-w-none leading-relaxed text-ink dark:text-dark-ink
                       [&_h1]:text-2xl [&_h1]:font-serif [&_h1]:font-semibold [&_h1]:mt-8 [&_h1]:mb-4
@@ -953,10 +975,10 @@ export default function InsightsPage() {
                       [&_hr]:border-border [&_hr]:my-6
                       [&_[data-callout-type]]:p-4 [&_[data-callout-type]]:rounded-lg [&_[data-callout-type]]:my-4
                       [&_div[data-type='toggle-block']]:my-3
-                      [&_div[data-type='toggle-block']_details]:rounded-lg [&_div[data-type='toggle-block']_details]:border [&_div[data-type='toggle-block']_details]:border-border
-                      [&_[data-math]]:my-4 [&_[data-math]]:text-center"
+                      [&_div[data-type='toggle-block']_details]:rounded-lg [&_div[data-type='toggle-block']_details]:border [&_div[data-type='toggle-block']_details]:border-border"
                     dangerouslySetInnerHTML={{ __html: DOMPurify.sanitize(peekNote.content) }}
                   />
+                  )
                 ) : (
                   <p className="text-sm text-concrete italic">—</p>
                 )}