feat: 添加Neo4j图数据库支持及前端代码重构

- 新增 Neo4j 图数据库 handler、service、model
- 后端添加 SaveGraph API 接口
- 前端 Database.vue 重构，拆分为独立组件
- 新增 web/src/views/database/ 组件目录
- 删除临时文件 (temp_*.go)
- 添加 Neo4j 相关 API 需求文档

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

server/internal/handler/neo4j_handler.go

@@ -0,0 +1,86 @@
+package handler
+
+import (
+	"net/http"
+
+	"x-agents/server/internal/model"
+	"x-agents/server/internal/service"
+
+	"github.com/gin-gonic/gin"
+)
+
+type Neo4jHandler struct {
+	service *service.Neo4jService
+}
+
+func NewNeo4jHandler(svc *service.Neo4jService) *Neo4jHandler {
+	return &Neo4jHandler{service: svc}
+}
+
+// Check 检查 Neo4j 连接
+func (h *Neo4jHandler) Check(c *gin.Context) {
+	var req model.Neo4jCheckRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	result, err := h.service.Check(req)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, result)
+}
+
+// GetGraphs 获取图谱概览数据
+func (h *Neo4jHandler) GetGraphs(c *gin.Context) {
+	var req model.Neo4jGraphRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	result, err := h.service.GetGraphs(req)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, result)
+}
+
+// GetNodes 获取节点详情
+func (h *Neo4jHandler) GetNodes(c *gin.Context) {
+	var req model.Neo4jNodeRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	result, err := h.service.GetNodes(req)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, result)
+}
+
+// GetRelationships 获取关系详情
+func (h *Neo4jHandler) GetRelationships(c *gin.Context) {
+	var req model.Neo4jRelRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	result, err := h.service.GetRelationships(req)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, result)
+}