新增单元测试验证图片重定向逻辑，优化前端预览链接样式，调整依赖配置

go.mod

@@ -10,6 +10,7 @@ require (
 	github.com/glebarez/sqlite v1.11.0
 	github.com/robfig/cron/v3 v3.0.1
 	github.com/spf13/viper v1.21.0
+	github.com/stretchr/testify v1.11.1
 	github.com/studio-b12/gowebdav v0.12.0
 	github.com/swaggo/files v1.0.1
 	github.com/swaggo/gin-swagger v1.6.1
@@ -29,6 +30,7 @@ require (
 	github.com/bytedance/sonic v1.14.0 // indirect
 	github.com/bytedance/sonic/loader v0.3.0 // indirect
 	github.com/cloudwego/base64x v0.1.6 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.8 // indirect
 	github.com/gin-contrib/sse v1.1.0 // indirect
@@ -61,6 +63,7 @@ require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/quic-go/qpack v0.5.1 // indirect
 	github.com/quic-go/quic-go v0.54.0 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
@@ -85,6 +88,7 @@ require (
 	golang.org/x/tools v0.40.0 // indirect
 	google.golang.org/protobuf v1.36.9 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 	modernc.org/libc v1.22.5 // indirect
 	modernc.org/mathutil v1.5.0 // indirect
 	modernc.org/memory v1.5.0 // indirect