refactor: factorisation peek panel — NotePeekPanel réutilisable

Architecture:
- components/note-peek/use-note-peek.ts: hook (fetch + state + events)
- components/note-peek/note-peek-content.tsx: rendu markdown/richtext/KaTeX
- components/note-peek/note-peek-panel.tsx: panel (overlay + inline modes)
- components/note-peek/index.ts: exports
- lib/use-scroll-to-block.ts: utilitaire scroll vers data-id

insights/page.tsx:
- ~95 lignes (state + fetch + KaTeX useEffect + AnimatePresence) → 10 lignes
- peek.open(noteId) remplace handleNoteClick complexe
- <NotePeekPanel mode=overlay /> remplace tout le JSX du panel

NotePeekPanel gère:
- markdown (MarkdownContent) + richtext (DOMPurify + KaTeX lazy)
- RTL (slide gauche pour fa/ar)
- prefers-reduced-motion
- role=dialog + aria-modal (overlay mode)
- loading spinner
- bouton Maximize2 + X
- renderContent prop pour custom (éditeur read-only)

memento-note/components/note-peek/note-peek-content.tsx

@@ -0,0 +1,66 @@
+'use client'
+
+import { useEffect, useRef, type ReactNode } from 'react'
+import DOMPurify from 'dompurify'
+import { MarkdownContent } from '@/components/markdown-content'
+import 'katex/dist/katex.min.css'
+import type { Note } from '@/lib/types'
+
+interface NotePeekContentProps {
+  note: Note
+  className?: string
+  children?: ReactNode
+}
+
+export function NotePeekContent({ note, className, children }: NotePeekContentProps) {
+  const htmlRef = useRef<HTMLDivElement>(null)
+
+  useEffect(() => {
+    if (!htmlRef.current || note.isMarkdown) return
+    let cancelled = false
+    void (async () => {
+      const katex = (await import('katex')).default
+      if (cancelled || !htmlRef.current) return
+      htmlRef.current.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 {}
+      })
+    })()
+    return () => { cancelled = true }
+  }, [note.id, note.content, note.isMarkdown])
+
+  if (children) return <>{children}</>
+
+  if (note.isMarkdown) {
+    return <MarkdownContent content={note.content} className={className} />
+  }
+
+  return (
+    <div
+      ref={htmlRef}
+      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
+        [&_h2]:text-xl [&_h2]:font-serif [&_h2]:font-semibold [&_h2]:mt-6 [&_h2]:mb-3
+        [&_h3]:text-lg [&_h3]:font-semibold [&_h3]:mt-5 [&_h3]:mb-2
+        [&_p]:my-3 [&_p]:leading-relaxed
+        [&_ul]:list-disc [&_ul]:ps-6 [&_ul]:my-3
+        [&_ol]:list-decimal [&_ol]:ps-6 [&_ol]:my-3
+        [&_li]:my-1
+        [&_blockquote]:border-l-4 [&_blockquote]:border-brand-accent [&_blockquote]:ps-4 [&_blockquote]:italic [&_blockquote]:text-muted-foreground [&_blockquote]:my-4
+        [&_pre]:bg-zinc-100 [&_pre]:dark:bg-zinc-900 [&_pre]:p-4 [&_pre]:rounded-lg [&_pre]:overflow-x-auto [&_pre]:text-sm [&_pre]:my-4
+        [&_code]:bg-zinc-100 [&_code]:dark:bg-zinc-800 [&_code]:px-1.5 [&_code]:py-0.5 [&_code]:rounded [&_code]:text-sm [&_code]:font-mono
+        [&_a]:text-blue-600 [&_a]:underline
+        [&_img]:rounded-lg [&_img]:max-w-full [&_img]:my-4
+        [&_table]:w-full [&_table]:my-4 [&_table]:border-collapse
+        [&_th]:border [&_th]:border-border [&_th]:p-2 [&_th]:bg-muted [&_th]:font-semibold [&_th]:text-left
+        [&_td]:border [&_td]:border-border [&_td]:p-2
+        [&_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 ${className || ''}`}
+      dangerouslySetInnerHTML={{ __html: DOMPurify.sanitize(note.content) }}
+    />
+  )
+}