fix(log): ES 7.2.0 time format .SSSZ + index dropdown + demo always visible

- ES query 502 fix: remove +00:00 conversion, use native .SSSZ format
  (ES 7.2.0 date_time = strict_date_optional_time only, rejects +00:00/epoch)
- parseLogTime: use time.RFC3339Nano for fractional seconds
- new API GET /log-datasources/indices to list ES indices via proxy
- LogDatasourceDialog: add '获取索引' button + Select dropdown for ES
- LogDatasourcePage: always show demo sources alongside real ones

backend/controller/log_datasource.go

@@ -3,6 +3,7 @@ package controller
 import (
 	"crypto/tls"
 	"encoding/base64"
+	"encoding/json"
 	"io"
 	"net/http"
 	"strings"
@@ -168,6 +169,52 @@ func (h *LogDSHandler) TestConnection(c *gin.Context) {
 	c.JSON(200, model.Response{Code: 200, Message: "连接成功", Data: map[string]string{"status": "ok"}})
 }
 
+// ListIndices GET /api/v1/log-datasources/indices?url=...&type=elasticsearch
+// 通过代理查询 ES 集群的索引列表 // Logan.Li
+func (h *LogDSHandler) ListIndices(c *gin.Context) {
+	esURL := c.Query("url")
+	if esURL == "" {
+		c.JSON(400, model.Response{Code: 400, Message: "url 参数必填"})
+		return
+	}
+	basicAuth := c.Query("basic_auth") == "true"
+	user := c.Query("basic_auth_user")
+	pass := c.Query("basic_auth_pass")
+	skipTLS := c.Query("skip_tls_verify") == "true"
+
+	client := newLogHTTPClient(skipTLS, 10*time.Second)
+	target := strings.TrimRight(esURL, "/") + "/_cat/indices?format=json&h=index"
+	httpReq, err := http.NewRequest(http.MethodGet, target, nil)
+	if err != nil {
+		c.JSON(502, model.Response{Code: 502, Message: err.Error()})
+		return
+	}
+	applyLogDSAuth(httpReq, basicAuth, user, pass)
+	resp, err := client.Do(httpReq)
+	if err != nil {
+		c.JSON(502, model.Response{Code: 502, Message: "查询索引失败: " + err.Error()})
+		return
+	}
+	defer resp.Body.Close()
+	body, _ := io.ReadAll(resp.Body)
+	if resp.StatusCode >= 400 {
+		c.JSON(502, model.Response{Code: 502, Message: "ES 错误: " + string(body)})
+		return
+	}
+	var raw []map[string]interface{}
+	if err := json.Unmarshal(body, &raw); err != nil {
+		c.JSON(502, model.Response{Code: 502, Message: "解析索引列表失败"})
+		return
+	}
+	indices := make([]string, 0, len(raw))
+	for _, entry := range raw {
+		if idx, ok := entry["index"].(string); ok {
+			indices = append(indices, idx)
+		}
+	}
+	c.JSON(200, model.Response{Code: 200, Data: indices})
+}
+
 func testLogDSConnection(req model.TestLogDSReq) (bool, string) {
 	client := newLogHTTPClient(req.SkipTLSVerify, 10*time.Second)
 	url := strings.TrimRight(req.URL, "/")

backend/controller/log_proxy.go

@@ -149,10 +149,7 @@ func (h *LogProxyHandler) QueryES(c *gin.Context) {
 			},
 		}
 		if req.Start != "" || req.End != "" {
-			// ES 7.2 date_time 格式要求 +00:00 而非 Z；兼容 @timestamp 与 timestamp // Logan.Li
-			buildRangeVal := func(v string) string {
-				return strings.Replace(v, "Z", "+00:00", 1)
-			}
+			// ES 7.2 date_time 仅接受 .SSSZ 格式；兼容 @timestamp 与 timestamp // Logan.Li
 			rangeCond := map[string]interface{}{
 				"bool": map[string]interface{}{
 					"should": []interface{}{
@@ -167,10 +164,10 @@ func (h *LogProxyHandler) QueryES(c *gin.Context) {
 				for _, v := range rng {
 					r := v.(map[string]string)
 					if req.Start != "" {
-						r["gte"] = buildRangeVal(req.Start)
+						r["gte"] = req.Start
 					}
 					if req.End != "" {
-						r["lte"] = buildRangeVal(req.End)
+						r["lte"] = req.End
 					}
 				}
 			}
@@ -217,9 +214,8 @@ func parseLogTime(s string) (time.Time, error) {
 		}
 		return time.Unix(n, 0), nil
 	}
-	// ES 7.2 date_time 不接受 Z，转 +00:00
-	s = strings.Replace(s, "Z", "+00:00", 1)
-	return time.Parse(time.RFC3339, s)
+	// 解析 ISO8601（含 .SSSZ 毫秒后缀，如 2026-06-20T09:33:17.000Z）
+	return time.Parse(time.RFC3339Nano, s)
 }
 
 func defaultESQuery(q string) string {

backend/router/routes.go

@@ -721,6 +721,7 @@ func Register(r *gin.Engine, db *gorm.DB, log *zap.Logger, cfg *config.Config, c
 	logDSGroup := authorized.Group("/log-datasources")
 	{
 		logDSGroup.GET("", logDSHandler.List)
+		logDSGroup.GET("/indices", logDSHandler.ListIndices)
 		logDSGroup.GET("/:id", logDSHandler.Get)
 		logDSGroup.POST("", logDSHandler.Create)
 		logDSGroup.PUT("/:id", logDSHandler.Update)