feat: 블로그 글 하단에 원문 출처 링크 표시

- 본문 끝에 출처 박스 추가 (배경색 + 좌측 보더)
- sources 배열과 source_url 모두 표시
- 중복 URL 제거, 새 탭 열기(target=_blank)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

bots/publisher_bot.py

@@ -301,8 +301,32 @@ def build_full_html(article: dict, body_html: str, toc_html: str) -> str:
     if toc_html:
         html_parts.append(f'<div class="toc-wrapper">{toc_html}</div>')
     html_parts.append(body_html)
+
+    # 원문 출처 링크
+    sources = article.get('sources', [])
+    source_url = article.get('source_url', '')
+    source_name = article.get('source_name', '') or article.get('source', '')
+    if sources or source_url:
+        html_parts.append('<hr/>')
+        html_parts.append('<div class="source-info" style="margin:1.5em 0;padding:1em;'
+                          'background:#f8f9fa;border-left:4px solid #ddd;border-radius:4px;'
+                          'font-size:0.9em;color:#555;">')
+        html_parts.append('<b>📌 원문 출처</b><br/>')
+        seen = set()
+        if sources:
+            for src in sources:
+                url = src.get('url', '')
+                title = src.get('title', '') or url
+                if url and url not in seen:
+                    seen.add(url)
+                    html_parts.append(f'• <a href="{url}" target="_blank" rel="noopener">{title}</a><br/>')
+        if source_url and source_url not in seen:
+            label = source_name or source_url
+            html_parts.append(f'• <a href="{source_url}" target="_blank" rel="noopener">{label}</a><br/>')
+        html_parts.append('</div>')
+
     if disclaimer:
-        html_parts.append(f'<hr/><p class="disclaimer"><small>{disclaimer}</small></p>')
+        html_parts.append(f'<p class="disclaimer"><small>{disclaimer}</small></p>')
 
     return '\n'.join(html_parts)