feat: 自动备份与保留策略、健康持续化与状态页、指标历史与趋势图，并修隧道判定误报与仪表盘布局（v1.2.11）

- 自动备份：每日一份（按最新备份是否在 24h 内判定，重启不重复）、保留份数可配、列表/下载/恢复/删除，恢复前先校验归档；顺手修 writeArchive 逐个检查 tar/gzip/文件 Close()（审查报告 §二）

- 健康持续化：只存状态变更（up/down/unknown）并推导可用率与不可用区间；公开状态页默认关闭、访问码存 SHA-256、按 IP 限流、只暴露域名与可用率

- 隧道判定修复：RouteHealthCandidate 新增 tunnel_known，frps 管理接口不可用时不再把「判不出来」当成「不通」（此前会误报「隧道连续不通」）；汇总与徽标同样区分「无法判定」

- 指标历史：metrics_samples 纵向点表（本机 CPU/内存/磁盘 + 每规则上下行，30 天保留、查询按桶平均、不做降采样表）；仪表盘趋势卡支持 1h/24h/7d

- 仪表盘布局：运行状态并入顶部统计区（运行时长补进「服务」卡）；性能并入系统资源那一行，整行 4 列

- 测试：backup/metrics/frp/api/app 新增用例；gofmt、go build/vet/test、vue-tsc、vite build 全绿

- agent 无改动，AgentVersion 保持 0.12.2

internal/api/backup_handler.go

@@ -7,14 +7,16 @@ import (
 	"path/filepath"
 
 	"github.com/fonu/fonu/internal/backup"
+	"github.com/fonu/fonu/internal/settings"
 )
 
 type BackupHandler struct {
-	svc *backup.Service
+	svc      *backup.Service
+	settings *settings.Store
 }
 
-func NewBackupHandler(svc *backup.Service) *BackupHandler {
-	return &BackupHandler{svc: svc}
+func NewBackupHandler(svc *backup.Service, settingsStore *settings.Store) *BackupHandler {
+	return &BackupHandler{svc: svc, settings: settingsStore}
 }
 
 func (h *BackupHandler) Export(w http.ResponseWriter, r *http.Request) {
@@ -72,3 +74,94 @@ func (h *BackupHandler) Restore(w http.ResponseWriter, r *http.Request) {
 	_ = os.Remove(tmpPath)
 	writeJSON(w, http.StatusOK, map[string]string{"message": "备份已恢复，建议重启 Fonu"})
 }
+
+// ListArchives 列出留在磁盘上的备份（自动备份 + 手动「立即备份」）。
+// 与「立即下载」不同：这些文件长期留在 <DataDir>/backups 下。
+func (h *BackupHandler) ListArchives(w http.ResponseWriter, r *http.Request) {
+	archives, err := h.svc.List()
+	if err != nil {
+		writeError(r, w, http.StatusInternalServerError, "读取备份列表失败", err)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{
+		"archives": archives,
+		"keep":     backup.KeepCount(r.Context(), h.settings),
+	})
+}
+
+// CreateArchive 立即备份一份并保留在服务器上，顺带按保留份数剪枝
+func (h *BackupHandler) CreateArchive(w http.ResponseWriter, r *http.Request) {
+	path, err := h.svc.Export(r.Context())
+	if err != nil {
+		writeError(r, w, http.StatusInternalServerError, "创建备份失败", err)
+		return
+	}
+	name := filepath.Base(path)
+	// 写失败的备份不能留在列表里冒充可用备份
+	if _, err := h.svc.Verify(r.Context(), path); err != nil {
+		_ = h.svc.Remove(name)
+		writeError(r, w, http.StatusInternalServerError, "备份校验失败："+err.Error(), err)
+		return
+	}
+	removed, err := h.svc.Prune(backup.KeepCount(r.Context(), h.settings))
+	if err != nil {
+		writeError(r, w, http.StatusInternalServerError, "备份已创建，但清理旧备份失败："+err.Error(), err)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"name": name, "removed": removed})
+}
+
+// DownloadArchive 下载指定备份；用 ServeContent 支持断点续传
+func (h *BackupHandler) DownloadArchive(w http.ResponseWriter, r *http.Request) {
+	path, err := h.svc.Path(r.PathValue("name"))
+	if err != nil {
+		writeError(r, w, http.StatusBadRequest, err.Error())
+		return
+	}
+	file, err := os.Open(path)
+	if err != nil {
+		writeError(r, w, http.StatusNotFound, "备份不存在")
+		return
+	}
+	defer file.Close()
+	info, err := file.Stat()
+	if err != nil {
+		writeError(r, w, http.StatusInternalServerError, "读取备份失败", err)
+		return
+	}
+	w.Header().Set("Content-Type", "application/gzip")
+	w.Header().Set("Content-Disposition", "attachment; filename="+filepath.Base(path))
+	http.ServeContent(w, r, filepath.Base(path), info.ModTime(), file)
+}
+
+// RestoreArchive 从指定备份恢复。恢复会覆盖数据库与证书，前端必须二次确认
+func (h *BackupHandler) RestoreArchive(w http.ResponseWriter, r *http.Request) {
+	path, err := h.svc.Path(r.PathValue("name"))
+	if err != nil {
+		writeError(r, w, http.StatusBadRequest, err.Error())
+		return
+	}
+	// 恢复前先校验：半个包不能拿去覆盖现有数据
+	if _, err := h.svc.Verify(r.Context(), path); err != nil {
+		writeError(r, w, http.StatusBadRequest, "该备份不可用："+err.Error(), err)
+		return
+	}
+	if err := h.svc.Restore(r.Context(), path); err != nil {
+		writeError(r, w, http.StatusBadRequest, err.Error(), err)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]string{"message": "备份已恢复，建议重启 Fonu"})
+}
+
+// DeleteArchive 删除指定备份
+func (h *BackupHandler) DeleteArchive(w http.ResponseWriter, r *http.Request) {
+	if err := h.svc.Remove(r.PathValue("name")); err != nil {
+		if err.Error() == "备份不存在" {
+			writeError(r, w, http.StatusNotFound, err.Error())
+			return
+		}
+		writeError(r, w, http.StatusBadRequest, err.Error())
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"ok": true})
+}