feat: 뉴스 전용 뷰어 + 카드 구분 + 설정 UI

- DocumentViewer: source_channel=news → article 전용 뷰어
  (제목/소스/날짜/요약/원문 링크 rel=noopener)
- DocumentCard: 뉴스 카드에 📰 아이콘
- settings: 뉴스 소스 관리 (목록/추가/삭제/토글/수집/마지막 시간)

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

frontend/src/lib/components/DocumentCard.svelte

@@ -96,6 +96,9 @@
 
   <!-- 우측 메타 -->
   <div class="shrink-0 flex flex-col items-end gap-1 text-[10px]">
+    {#if doc.source_channel === 'news' && doc.edit_url}
+      <span class="text-blue-400">📰</span>
+    {/if}
     {#if doc.score !== undefined}
       <span class="text-[var(--accent)] font-medium">{(doc.score * 100).toFixed(0)}%</span>
     {/if}

frontend/src/lib/components/DocumentViewer.svelte

@@ -62,7 +62,7 @@
     loading = true;
     try {
       fullDoc = await api(`/documents/${id}`);
-      viewerType = getViewerType(fullDoc.file_format);
+      viewerType = fullDoc.source_channel === 'news' ? 'article' : getViewerType(fullDoc.file_format);
 
       // Markdown: extracted_text 없으면 원본 파일 직접 가져오기
       if (viewerType === 'markdown' && !fullDoc.extracted_text) {
@@ -232,6 +232,34 @@
             class="px-3 py-1.5 text-sm bg-[var(--accent)] text-white rounded hover:bg-[var(--accent-hover)]"
           >AutoCAD Web에서 열기</a>
         </div>
+      {:else if viewerType === 'article'}
+        <!-- 뉴스 전용 뷰어 -->
+        <div class="p-5 max-w-3xl mx-auto">
+          <h1 class="text-lg font-bold mb-2">{fullDoc.title}</h1>
+          <div class="flex items-center gap-2 mb-4 text-xs text-[var(--text-dim)]">
+            {#if fullDoc.ai_tags?.length}
+              {#each fullDoc.ai_tags.filter(t => t.startsWith('News/')) as tag}
+                <span class="px-1.5 py-0.5 rounded bg-blue-900/30 text-blue-400">{tag.replace('News/', '')}</span>
+              {/each}
+            {/if}
+            <span>{new Date(fullDoc.created_at).toLocaleDateString('ko-KR', { year: 'numeric', month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit' })}</span>
+          </div>
+          <div class="markdown-body mb-6">
+            {@html renderMd(fullDoc.extracted_text || '')}
+          </div>
+          <div class="flex items-center gap-3 pt-4 border-t border-[var(--border)]">
+            {#if fullDoc.edit_url}
+              <a
+                href={fullDoc.edit_url}
+                target="_blank"
+                rel="noopener noreferrer"
+                class="flex items-center gap-1 px-3 py-1.5 text-sm bg-[var(--accent)] text-white rounded-lg hover:bg-[var(--accent-hover)]"
+              >
+                <ExternalLink size={14} /> 원문 보기
+              </a>
+            {/if}
+          </div>
+        </div>
       {:else}
         <div class="flex items-center justify-center h-full">
           <p class="text-sm text-[var(--text-dim)]">미리보기를 지원하지 않는 형식입니다 ({fullDoc.file_format})</p>