feat: 平台配置全面生效 — 配置策略接入实际逻辑

- query组: ExecuteQuery读取query_limit_max/query_timeout/query_dangerous_pattern
  - 查询超时通过context.WithTimeout生效，db.QueryContext/QueryRowContext
  - 危险模式检测拦截无WHERE的DELETE/UPDATE/DROP/TRUNCATE
  - LIMIT上限从settings读取，不再硬编码1000

- security组: Login读取login_max_attempts/login_lockout_minutes
  - 新增User字段: failed_login_attempts + locked_until
  - 登录失败达到阈值自动锁定，成功时清除计数
  - JWT Token过期时间读取session_timeout_hours设置

- executor组: ExecuteTicket读取executor_timeout/executor_dry_run
  - 执行超时通过context.WithTimeout控制
  - 开启dry_run时先EXPLAIN预检查SQL语法
  - db.ExecContext替代db.Exec

- cleanup组: SettingsCleanupPreview/Run从占位改为真实实现
  - 预览统计4类数据(工单/查询历史/慢日志/审计日志)待清理数量
  - 执行清理按retention_days配置删除过期数据

- ghost组: 13项gh-ost配置加入seedDefaultSettings
  - enabled/path/mode/osc_priority/env/cloud/trigger/chunk/load/lag等
  - 已被ghost.go中getGhostConfig等函数读取

- 前端: PlatformConfigPage新增Ghost/OSC分组显示

backend/internal/handler/connection_tester.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"math"
 	"strconv"
 	"strings"
 	"time"
@@ -230,7 +231,7 @@ func getRedisMetrics(instance *model.Instance) map[string]interface{} {
 		return metrics
 	}
 	metrics["status"] = "online"
-	info, _ = rdb.Info(ctx, "server", "clients", "stats").Result()
+	info, _ = rdb.Info(ctx, "server", "clients", "stats", "memory", "cpu").Result()
 	// Latency from PING
 	start := time.Now()
 	rdb.Ping(ctx)
@@ -274,6 +275,48 @@ func getRedisMetrics(instance *model.Instance) map[string]interface{} {
 			metrics["uptime"] = fmt.Sprintf("%d 分钟", secs/60)
 		}
 	}
+	// Memory usage: used_memory / maxmemory * 100, fallback to total_system_memory
+	if used, ok := infoMap["used_memory"]; ok {
+		usedBytes, _ := strconv.ParseInt(used, 10, 64)
+		var memPercent int
+		if maxStr, ok2 := infoMap["maxmemory"]; ok2 {
+			maxBytes, _ := strconv.ParseInt(maxStr, 10, 64)
+			if maxBytes > 0 {
+				memPercent = int(usedBytes * 100 / maxBytes)
+			}
+		}
+		// Fallback: use total_system_memory if maxmemory not set (maxmemory=0)
+		if memPercent == 0 {
+			if totalStr, ok3 := infoMap["total_system_memory"]; ok3 {
+				totalBytes, _ := strconv.ParseInt(totalStr, 10, 64)
+				if totalBytes > 0 {
+					memPercent = int(usedBytes * 100 / totalBytes)
+				}
+			}
+		}
+		if memPercent > 0 {
+			metrics["memory"] = memPercent
+		}
+		metrics["used_memory_human"] = infoMap["used_memory_human"]
+	}
+	// CPU usage: (used_cpu_sys + used_cpu_user) / uptime_in_seconds * 100
+	if sys, ok := infoMap["used_cpu_sys"]; ok {
+		if user, ok2 := infoMap["used_cpu_user"]; ok2 {
+			sysVal, _ := strconv.ParseFloat(sys, 64)
+			userVal, _ := strconv.ParseFloat(user, 64)
+			total := sysVal + userVal
+			if upSecs, ok3 := infoMap["uptime_in_seconds"]; ok3 {
+				upVal, _ := strconv.ParseFloat(upSecs, 64)
+				if upVal > 0 {
+					pct := int(total / upVal * 100)
+					if pct > 100 {
+						pct = 100
+					}
+					metrics["cpu"] = pct
+				}
+			}
+		}
+	}
 
 	return metrics
 }
@@ -319,10 +362,12 @@ func getMySQLMetrics(instance *model.Instance) map[string]interface{} {
 	metrics["latency"] = time.Since(start).Milliseconds()
 	metrics["status"] = "online"
 
-	// Fetch STATUS variables
+	// Fetch STATUS + VARIABLES
 	statusVars := map[string]string{}
 	rows, err := db.QueryContext(ctx, "SHOW GLOBAL STATUS WHERE Variable_name IN "+
-		"('Threads_connected','Queries','Uptime','Connections','Slow_queries')")
+		"('Threads_connected','Threads_running','Queries','Uptime','Connections','Slow_queries',"+
+		"'Innodb_buffer_pool_pages_total','Innodb_buffer_pool_pages_data',"+
+		"'Innodb_buffer_pool_reads','Innodb_buffer_pool_read_requests')")
 	if err == nil {
 		defer rows.Close()
 		for rows.Next() {
@@ -331,10 +376,33 @@ func getMySQLMetrics(instance *model.Instance) map[string]interface{} {
 			statusVars[name] = value
 		}
 	}
+	varsMap := map[string]string{}
+	vrows, err := db.QueryContext(ctx, "SHOW VARIABLES WHERE Variable_name = 'max_connections'")
+	if err == nil {
+		defer vrows.Close()
+		for vrows.Next() {
+			var name, value string
+			vrows.Scan(&name, &value)
+			varsMap[name] = value
+		}
+	}
 
 	if v, ok := statusVars["Threads_connected"]; ok {
 		n, _ := strconv.Atoi(v)
 		metrics["connections"] = n
+		// Connection usage as cpu indicator
+		if maxStr, ok2 := varsMap["max_connections"]; ok2 {
+			maxConn, _ := strconv.Atoi(maxStr)
+			if maxConn > 0 {
+				metrics["cpu"] = int(math.Ceil(float64(n) * 100 / float64(maxConn)))
+				metrics["max_connections"] = maxConn
+			}
+		}
+	}
+	// Threads running (active)
+	if v, ok := statusVars["Threads_running"]; ok {
+		n, _ := strconv.Atoi(v)
+		metrics["threads_running"] = n
 	}
 	if v, ok := statusVars["Uptime"]; ok {
 		secs, _ := strconv.Atoi(v)
@@ -356,6 +424,27 @@ func getMySQLMetrics(instance *model.Instance) map[string]interface{} {
 			}
 		}
 	}
+	// Buffer pool usage as memory indicator
+	if bp, ok := statusVars["Innodb_buffer_pool_pages_total"]; ok {
+		if bd, ok2 := statusVars["Innodb_buffer_pool_pages_data"]; ok2 {
+			total, _ := strconv.ParseFloat(bp, 64)
+			used, _ := strconv.ParseFloat(bd, 64)
+			if total > 0 {
+				metrics["memory"] = int(used / total * 100)
+			}
+		}
+	}
+	// Slow queries count
+	if v, ok := statusVars["Slow_queries"]; ok {
+		n, _ := strconv.Atoi(v)
+		metrics["slow_queries"] = n
+	}
+	// Data size on disk
+	var dataMB float64
+	db.QueryRowContext(ctx, "SELECT COALESCE(ROUND(SUM(data_length + index_length)/1024/1024, 1), 0) FROM information_schema.tables WHERE table_schema NOT IN ('mysql','information_schema','performance_schema','sys')").Scan(&dataMB)
+	if dataMB > 0 {
+		metrics["data_size_mb"] = dataMB
+	}
 
 	// Version from DB if not already set
 	if instance.Version == nil || *instance.Version == "" {