fix(reliability): 采集器并发去重 + 备份恢复即时重载 + context 贯穿请求链

- CollectorService 安装/卸载按采集器互斥去重(重复触发不再并发 docker rm/run 互踩);删除后卸载失败留日志
- ApplyStagedBackup 替换文件后立即 Reload 内存态,消除「重启前旧内存落盘覆盖恢复文件」竞态;暂存文件名升级 lokistack.json(兼容旧名)
- GetUsage/Validate 全链路 context 贯穿:请求取消即中止 SSH/k8s 查询(异步调用点显式 Background)

backend/repository/db.go

@@ -264,11 +264,6 @@ func (d *JsonDB) fixUnreachableLogSourceURLs() {
 //	LogSource   : 查询页数据源下拉选不动（两个 option 同 value）
 //	AlertRule   : 规则列表出现两条同 id，编辑/删除操作命中错的那条
 //	NotifyChannel: 通知渠道覆盖错对象
-func (d *JsonDB) dedupeCollectionIDs() {
-	d.dedupeLogSourceIDs()
-	d.dedupeAlertRuleIDs()
-	d.dedupeNotifyChannelIDs()
-}
 
 // dedupeAlertRuleIDs 重新编号重复的告警规则 ID。
 // 同名规则（seed 重复执行导致）只保留第一条，其余删除。
@@ -539,6 +534,108 @@ func (d *JsonDB) migrateSchema() bool {
 	return true
 }
 
+// Reload 从磁盘重新加载内存态(备份恢复后调用):
+// 成功解析才整体替换集合并重建 ID 序列;失败时保持原内存态并返回错误。
+// 必须在持有写锁的情况下调用。
+func (d *JsonDB) Reload() error {
+	data, err := os.ReadFile(d.dataFile)
+	if err != nil {
+		return err
+	}
+	var fresh JsonDB
+	if err := json.Unmarshal(data, &fresh); err != nil {
+		return err
+	}
+	d.Users = fresh.Users
+	d.Clusters = fresh.Clusters
+	d.Hosts = fresh.Hosts
+	d.Storages = fresh.Storages
+	d.Deployments = fresh.Deployments
+	d.Collectors = fresh.Collectors
+	d.Logs = fresh.Logs
+	d.Settings = fresh.Settings
+	d.LogSources = fresh.LogSources
+	d.AlertRules = fresh.AlertRules
+	d.AlertDeliveries = fresh.AlertDeliveries
+	d.NotifyChannels = fresh.NotifyChannels
+	d.LogPolicyGroups = fresh.LogPolicyGroups
+	d.AuditLogs = fresh.AuditLogs
+	d.DailyVolumeSnapshots = fresh.DailyVolumeSnapshots
+	d.SchemaVersion = fresh.SchemaVersion
+	d.sequences = map[string]uint{}
+	for _, u := range d.Users {
+		if u.ID > d.sequences["users"] {
+			d.sequences["users"] = u.ID
+		}
+	}
+	for _, cl := range d.Clusters {
+		if cl.ID > d.sequences["clusters"] {
+			d.sequences["clusters"] = cl.ID
+		}
+	}
+	for _, h := range d.Hosts {
+		if h.ID > d.sequences["hosts"] {
+			d.sequences["hosts"] = h.ID
+		}
+	}
+	for _, s := range d.Storages {
+		if s.ID > d.sequences["storages"] {
+			d.sequences["storages"] = s.ID
+		}
+	}
+	for _, de := range d.Deployments {
+		if de.ID > d.sequences["deployments"] {
+			d.sequences["deployments"] = de.ID
+		}
+	}
+	for _, col := range d.Collectors {
+		if col.ID > d.sequences["collectors"] {
+			d.sequences["collectors"] = col.ID
+		}
+	}
+	for _, l := range d.Logs {
+		if l.ID > d.sequences["logs"] {
+			d.sequences["logs"] = l.ID
+		}
+	}
+	for _, g := range d.LogPolicyGroups {
+		if g.ID > d.sequences["logPolicyGroups"] {
+			d.sequences["logPolicyGroups"] = g.ID
+		}
+	}
+	for _, s := range d.LogSources {
+		if s.ID > d.sequences["logSources"] {
+			d.sequences["logSources"] = s.ID
+		}
+	}
+	for _, ch := range d.NotifyChannels {
+		if ch.ID > d.sequences["notifyChannels"] {
+			d.sequences["notifyChannels"] = ch.ID
+		}
+	}
+	for _, r := range d.AlertRules {
+		if r.ID > d.sequences["alertRules"] {
+			d.sequences["alertRules"] = r.ID
+		}
+	}
+	for _, de := range d.AlertDeliveries {
+		if de.ID > d.sequences["alertDeliveries"] {
+			d.sequences["alertDeliveries"] = de.ID
+		}
+	}
+	for _, a := range d.AuditLogs {
+		if a.ID > d.sequences["auditLogs"] {
+			d.sequences["auditLogs"] = a.ID
+		}
+	}
+	for _, v := range d.DailyVolumeSnapshots {
+		if v.ID > d.sequences["dailyVolumeSnapshots"] {
+			d.sequences["dailyVolumeSnapshots"] = v.ID
+		}
+	}
+	return nil
+}
+
 // migrateLegacyDataFile 首次从历史命名(opsxloki.json / lokideploy.json)加载后,
 // 立即升级到 lokistack.json:数据原子写入新文件后删除旧文件。
 // 不迁移的话回退链会让旧文件名(旧品牌残留)一直被沿用下去。