feat: 添加图数据库表初始化脚本

- 新增 graph_nodes 表存储 NER 提取的命名实体
- 新增 graph_relations 表存储实体关系
- user_id 字段可为空，支持自动 NER 提取场景
- 使用 VARCHAR(36) 类型兼容现有表结构
- 包含条件外键约束和更新时间触发器

backend/sql/graph_tables.sql

@@ -0,0 +1,99 @@
+-- 灵越智报 v2.0 图数据库表结构
+-- PostgreSQL 15+
+-- 用于 NER 实体识别结果存储
+
+-- ============================================
+-- 1. 图节点表（graph_nodes）
+-- ============================================
+-- 存储从文档中提取的命名实体
+CREATE TABLE IF NOT EXISTS graph_nodes (
+    id VARCHAR(36) PRIMARY KEY,
+    document_id VARCHAR(36) NOT NULL,
+    user_id VARCHAR(36),  -- 可为空，自动提取时可能没有用户上下文
+    name VARCHAR(255) NOT NULL,
+    type VARCHAR(50) NOT NULL, -- text/table/image/number/date/ORG/PERSON/LOC/TIME/DEVICE/PROJECT/METHOD等
+    value TEXT,
+    position JSONB, -- {charStart, charEnd, line}
+    parent_id VARCHAR(36),
+    level INTEGER DEFAULT 0,
+    metadata JSONB DEFAULT '{}',
+    create_time TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    update_time TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+
+-- 添加外键约束（如果关联表存在）
+DO $$
+BEGIN
+    IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'documents') THEN
+        ALTER TABLE graph_nodes DROP CONSTRAINT IF EXISTS fk_graph_nodes_document;
+        ALTER TABLE graph_nodes ADD CONSTRAINT fk_graph_nodes_document
+            FOREIGN KEY (document_id) REFERENCES documents(id) ON DELETE CASCADE;
+    END IF;
+    
+    IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'users') THEN
+        ALTER TABLE graph_nodes DROP CONSTRAINT IF EXISTS fk_graph_nodes_user;
+        ALTER TABLE graph_nodes ADD CONSTRAINT fk_graph_nodes_user
+            FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL;
+    END IF;
+END $$;
+
+CREATE INDEX IF NOT EXISTS idx_graph_nodes_document_id ON graph_nodes(document_id);
+CREATE INDEX IF NOT EXISTS idx_graph_nodes_user_id ON graph_nodes(user_id);
+CREATE INDEX IF NOT EXISTS idx_graph_nodes_type ON graph_nodes(type);
+CREATE INDEX IF NOT EXISTS idx_graph_nodes_parent_id ON graph_nodes(parent_id);
+CREATE INDEX IF NOT EXISTS idx_graph_nodes_position ON graph_nodes USING GIN(position);
+
+-- ============================================
+-- 2. 图关系表（graph_relations）
+-- ============================================
+-- 存储实体之间的关系
+CREATE TABLE IF NOT EXISTS graph_relations (
+    id VARCHAR(36) PRIMARY KEY,
+    from_node_id VARCHAR(36) NOT NULL,
+    to_node_id VARCHAR(36) NOT NULL,
+    relation_type VARCHAR(50) NOT NULL, -- BELONGS_TO/USES/LOCATED_IN/EXECUTES/MONITORS等
+    action_type VARCHAR(50),
+    action_config JSONB,
+    order_index INTEGER DEFAULT 0,
+    condition_expr TEXT,
+    metadata JSONB DEFAULT '{}',
+    create_time TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    update_time TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT fk_graph_relations_from_node FOREIGN KEY (from_node_id) REFERENCES graph_nodes(id) ON DELETE CASCADE,
+    CONSTRAINT fk_graph_relations_to_node FOREIGN KEY (to_node_id) REFERENCES graph_nodes(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_graph_relations_from_node ON graph_relations(from_node_id);
+CREATE INDEX IF NOT EXISTS idx_graph_relations_to_node ON graph_relations(to_node_id);
+CREATE INDEX IF NOT EXISTS idx_graph_relations_type ON graph_relations(relation_type);
+
+-- ============================================
+-- 创建更新时间触发器函数（如果不存在）
+-- ============================================
+CREATE OR REPLACE FUNCTION update_updated_at_column()
+RETURNS TRIGGER AS $$
+BEGIN
+    NEW.update_time = CURRENT_TIMESTAMP;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+-- 创建触发器
+DROP TRIGGER IF EXISTS update_graph_nodes_updated_at ON graph_nodes;
+CREATE TRIGGER update_graph_nodes_updated_at 
+    BEFORE UPDATE ON graph_nodes
+    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();
+
+DROP TRIGGER IF EXISTS update_graph_relations_updated_at ON graph_relations;
+CREATE TRIGGER update_graph_relations_updated_at 
+    BEFORE UPDATE ON graph_relations
+    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();
+
+-- ============================================
+-- 说明
+-- ============================================
+-- 执行此脚本:
+-- psql -U lingyue -d lingyue_zhibao -f graph_tables.sql
+--
+-- 或在服务器上:
+-- psql -U postgres -d lingyue_zhibao -f graph_tables.sql