feat(trash): add bulk purge and automatic retention

internal/api/trash.go

@@ -0,0 +1,79 @@
+package api
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"time"
+)
+
+// JSON/JavaScript 共同精确表示的非负整数范围；不乘天数，避免期限溢出。
+const maxRetentionDays = 1<<53 - 1
+
+func trashRetentionDays(settings map[string]json.RawMessage) (int64, error) {
+	raw, ok := settings["trashRetentionDays"]
+	if !ok || bytes.Equal(raw, []byte("null")) {
+		return 30, nil
+	}
+	var days int64
+	if err := json.Unmarshal(raw, &days); err != nil || days < 0 || days > maxRetentionDays {
+		return 0, fmt.Errorf("回收站保留天数必须为非负安全整数，0 表示永不自动删除")
+	}
+	return days, nil
+}
+
+func (s *Server) trashClear(w http.ResponseWriter, r *http.Request) {
+	result, err := s.vault.PurgeTrash(0, time.Now())
+	if err != nil {
+		internalError(w, r, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, result)
+}
+
+func (s *Server) cleanupTrash(now time.Time) error {
+	// 与设置写入串行，避免在“永不删除”已保存后使用旧期限开始清理。
+	s.settingsMu.Lock()
+	defer s.settingsMu.Unlock()
+	settings, err := s.readSettings()
+	if err != nil {
+		return err
+	}
+	days, err := trashRetentionDays(settings)
+	if err != nil || days == 0 {
+		return err
+	}
+	result, err := s.vault.PurgeTrash(days, now)
+	if err != nil {
+		return err
+	}
+	if len(result.Failed) > 0 {
+		return fmt.Errorf("回收站清理部分失败: %v", result.Failed)
+	}
+	if len(result.Deleted) > 0 {
+		slog.Info("已清理过期回收站条目", "count", len(result.Deleted))
+	}
+	return nil
+}
+
+// RunTrashCleanup 启动时执行一次，其后每小时执行；不依赖浏览器在线。
+func (s *Server) RunTrashCleanup(ctx context.Context) {
+	ticker := time.NewTicker(time.Hour)
+	defer ticker.Stop()
+	for {
+		if ctx.Err() != nil {
+			return
+		}
+		if err := s.cleanupTrash(time.Now()); err != nil {
+			slog.Error("自动清理回收站失败", "err", err)
+		}
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+		}
+	}
+}