Add category view, pagination, and persist login across deployments

- Add 2-panel category view: sidebar tree + filtered item list
- Category counts use DISTINCT with descendant inclusion
- Hide empty categories, show category badges on item cards
- Add client-side pagination (10 items/page) for both views
- Persist access token in localStorage to survive page refresh
- Fix token refresh retry on backend restart

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

sundol-backend/src/main/java/com/sundol/controller/KnowledgeController.java

@@ -1,6 +1,7 @@
 package com.sundol.controller;
 
 import com.sundol.dto.IngestRequest;
+import com.sundol.repository.CategoryRepository;
 import com.sundol.service.KnowledgeService;
 import com.sundol.service.YouTubeTranscriptService;
 import org.slf4j.Logger;
@@ -22,11 +23,14 @@ public class KnowledgeController {
 
     private final KnowledgeService knowledgeService;
     private final YouTubeTranscriptService youTubeTranscriptService;
+    private final CategoryRepository categoryRepository;
 
     public KnowledgeController(KnowledgeService knowledgeService,
-                               YouTubeTranscriptService youTubeTranscriptService) {
+                               YouTubeTranscriptService youTubeTranscriptService,
+                               CategoryRepository categoryRepository) {
         this.knowledgeService = knowledgeService;
         this.youTubeTranscriptService = youTubeTranscriptService;
+        this.categoryRepository = categoryRepository;
     }
 
     @GetMapping
@@ -97,7 +101,28 @@ public class KnowledgeController {
                 .map(ResponseEntity::ok);
     }
 
-@GetMapping("/{id}/chunks")
+    @GetMapping("/categories")
+    public Mono<ResponseEntity<Map<String, Object>>> categories(@AuthenticationPrincipal String userId) {
+        return Mono.fromCallable(() -> {
+            var categories = categoryRepository.findAllByUserWithCount(userId);
+            var uncategorized = categoryRepository.findUncategorizedItems(userId);
+            return ResponseEntity.ok(Map.<String, Object>of(
+                    "categories", categories,
+                    "uncategorized", uncategorized
+            ));
+        }).subscribeOn(reactor.core.scheduler.Schedulers.boundedElastic());
+    }
+
+    @GetMapping("/categories/{categoryId}/items")
+    public Mono<ResponseEntity<List<Map<String, Object>>>> itemsByCategory(
+            @AuthenticationPrincipal String userId,
+            @PathVariable String categoryId) {
+        return Mono.fromCallable(() -> categoryRepository.findItemsByCategoryId(userId, categoryId))
+                .subscribeOn(reactor.core.scheduler.Schedulers.boundedElastic())
+                .map(ResponseEntity::ok);
+    }
+
+    @GetMapping("/{id}/chunks")
     public Mono<ResponseEntity<List<Map<String, Object>>>> getChunks(
             @AuthenticationPrincipal String userId,
             @PathVariable String id) {

sundol-backend/src/main/java/com/sundol/repository/CategoryRepository.java

@@ -110,6 +110,62 @@ public class CategoryRepository {
         );
     }
 
+    /**
+     * 카테고리 트리 + 해당 카테고리 및 하위 카테고리에 속한 고유 항목 수 조회
+     */
+    public List<Map<String, Object>> findAllByUserWithCount(String userId) {
+        return jdbcTemplate.queryForList(
+            "SELECT RAWTOHEX(c.id) AS id, c.name, RAWTOHEX(c.parent_id) AS parent_id, c.depth, c.full_path, " +
+            "  (SELECT COUNT(DISTINCT kic.knowledge_item_id) " +
+            "   FROM knowledge_item_categories kic " +
+            "   JOIN categories c2 ON c2.id = kic.category_id " +
+            "   WHERE c2.user_id = HEXTORAW(?) AND (c2.full_path = c.full_path OR c2.full_path LIKE c.full_path || '/%')) AS item_count " +
+            "FROM categories c WHERE c.user_id = HEXTORAW(?) ORDER BY c.full_path",
+            userId, userId
+        );
+    }
+
+    /**
+     * 특정 카테고리 및 하위 카테고리에 속한 knowledge_items 조회.
+     * full_path LIKE 'parent_path%' 로 하위 카테고리를 포함한다.
+     */
+    public List<Map<String, Object>> findItemsByCategoryId(String userId, String categoryId) {
+        // 먼저 선택된 카테고리의 full_path를 가져옴
+        var catResult = jdbcTemplate.queryForList(
+            "SELECT full_path FROM categories WHERE RAWTOHEX(id) = ?", categoryId
+        );
+        if (catResult.isEmpty()) return List.of();
+        String fullPath = (String) catResult.get(0).get("FULL_PATH");
+
+        return jdbcTemplate.queryForList(
+            "SELECT DISTINCT RAWTOHEX(ki.id) AS id, ki.type, ki.title, ki.source_url, ki.status, ki.created_at, " +
+            "  (SELECT LISTAGG(c2.full_path, ', ') WITHIN GROUP (ORDER BY c2.full_path) " +
+            "   FROM knowledge_item_categories kic2 JOIN categories c2 ON c2.id = kic2.category_id " +
+            "   WHERE kic2.knowledge_item_id = ki.id) AS categories " +
+            "FROM knowledge_items ki " +
+            "JOIN knowledge_item_categories kic ON kic.knowledge_item_id = ki.id " +
+            "JOIN categories c ON c.id = kic.category_id " +
+            "WHERE ki.user_id = HEXTORAW(?) AND (c.full_path = ? OR c.full_path LIKE ?) " +
+            "ORDER BY ki.created_at DESC",
+            userId, fullPath, fullPath + "/%"
+        );
+    }
+
+    /**
+     * 카테고리가 없는 knowledge_items 조회
+     */
+    public List<Map<String, Object>> findUncategorizedItems(String userId) {
+        return jdbcTemplate.queryForList(
+            "SELECT RAWTOHEX(ki.id) AS id, ki.type, ki.title, ki.source_url, ki.status, ki.created_at, " +
+            "  NULL AS categories " +
+            "FROM knowledge_items ki " +
+            "WHERE ki.user_id = HEXTORAW(?) " +
+            "AND NOT EXISTS (SELECT 1 FROM knowledge_item_categories kic WHERE kic.knowledge_item_id = ki.id) " +
+            "ORDER BY ki.created_at DESC",
+            userId
+        );
+    }
+
     /**
      * knowledge_item의 카테고리 매핑 전체 삭제
      */

sundol-backend/src/main/java/com/sundol/repository/KnowledgeRepository.java

@@ -32,24 +32,28 @@ public class KnowledgeRepository {
 
     public List<Map<String, Object>> list(String userId, String type, String status, String search) {
         StringBuilder sql = new StringBuilder(
-            "SELECT RAWTOHEX(id) AS id, type, title, source_url, status, created_at, updated_at FROM knowledge_items WHERE user_id = HEXTORAW(?)"
+            "SELECT RAWTOHEX(ki.id) AS id, ki.type, ki.title, ki.source_url, ki.status, ki.created_at, ki.updated_at, " +
+            "  (SELECT LISTAGG(c.full_path, ', ') WITHIN GROUP (ORDER BY c.full_path) " +
+            "   FROM knowledge_item_categories kic JOIN categories c ON c.id = kic.category_id " +
+            "   WHERE kic.knowledge_item_id = ki.id) AS categories " +
+            "FROM knowledge_items ki WHERE ki.user_id = HEXTORAW(?)"
         );
         java.util.List<Object> params = new java.util.ArrayList<>();
         params.add(userId);
 
         if (type != null && !type.isEmpty()) {
-            sql.append(" AND type = ?");
+            sql.append(" AND ki.type = ?");
             params.add(type);
         }
         if (status != null && !status.isEmpty()) {
-            sql.append(" AND status = ?");
+            sql.append(" AND ki.status = ?");
             params.add(status);
         }
         if (search != null && !search.isEmpty()) {
-            sql.append(" AND UPPER(title) LIKE UPPER(?)");
+            sql.append(" AND UPPER(ki.title) LIKE UPPER(?)");
             params.add("%" + search + "%");
         }
-        sql.append(" ORDER BY created_at DESC");
+        sql.append(" ORDER BY ki.created_at DESC");
 
         return jdbcTemplate.queryForList(sql.toString(), params.toArray());
     }