fix: AI 요약 마크다운 렌더링 — 상세페이지는 렌더링, 카드는 기호 제거

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

frontend/src/lib/components/DocumentCard.svelte

@@ -76,7 +76,7 @@
       {doc.title || '제목 없음'}
     </p>
     {#if doc.ai_summary}
-      <p class="text-xs text-[var(--text-dim)] truncate mt-0.5">{doc.ai_summary.slice(0, 100)}</p>
+      <p class="text-xs text-[var(--text-dim)] truncate mt-0.5">{doc.ai_summary.replace(/[*#_`~]/g, '').slice(0, 100)}</p>
     {/if}
     <div class="flex items-center gap-2 mt-1.5 flex-wrap">
       {#if showDomain && doc.ai_domain}

frontend/src/routes/documents/[id]/+page.svelte

@@ -131,7 +131,7 @@
         {#if doc.ai_summary}
           <div class="bg-[var(--surface)] rounded-xl border border-[var(--border)] p-5">
             <h3 class="text-sm font-semibold text-[var(--text-dim)] mb-2">AI 요약</h3>
-            <p class="text-sm leading-relaxed">{doc.ai_summary}</p>
+            <div class="text-sm leading-relaxed markdown-body">{@html renderMd(doc.ai_summary)}</div>
           </div>
         {/if}