feat: 내 글/댓글 모아보기 API

- GET /board/my/posts, /board/my/comments (페이징)
- PostSummary 에 category 추가, MyCommentResponse(글 제목·카테고리 포함)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/main/java/com/sb/web/board/service/BoardService.java

@@ -89,6 +89,22 @@ public class BoardService {
         return PageResponse.of(content, p, s, total);
     }
 
+    /** 내 글 모아보기 */
+    public PageResponse<PostSummary> myPosts(Long memberId, int page, int size) {
+        int p = Math.max(page, 1);
+        int s = Math.min(Math.max(size, 1), 100);
+        List<PostSummary> content = postMapper.findMyPage(memberId, (p - 1) * s, s);
+        return PageResponse.of(content, p, s, postMapper.countMyPosts(memberId));
+    }
+
+    /** 내 댓글 모아보기 */
+    public PageResponse<com.sb.web.board.dto.MyCommentResponse> myComments(Long memberId, int page, int size) {
+        int p = Math.max(page, 1);
+        int s = Math.min(Math.max(size, 1), 100);
+        var content = commentMapper.findMyPage(memberId, (p - 1) * s, s);
+        return PageResponse.of(content, p, s, commentMapper.countMyComments(memberId));
+    }
+
     private String normalizeSearchType(String t) {
         return ("content".equals(t) || "comment".equals(t)) ? t : "title";
     }