fix: 登录/注册支持 redirect 参数，未登录跳转自动携带来源页

- login.js/register.js 登录成功后优先跳转 redirect 参数指定页面
- 新增 common.RedirectToLogin 辅助函数，自动携带当前路径
- 替换所有 9 处硬编码 /auth/login 重定向

internal/controller/studio_controller.go

@@ -28,7 +28,7 @@ func NewStudioController(ps studioUseCase) *StudioController {
 func (ctrl *StudioController) OverviewPage(c *gin.Context) {
 	uid, _, ok := common.GetGinUser(c)
 	if !ok {
-		c.Redirect(http.StatusFound, "/auth/login")
+		common.RedirectToLogin(c)
 		return
 	}
 
@@ -56,7 +56,7 @@ func (ctrl *StudioController) OverviewPage(c *gin.Context) {
 func (ctrl *StudioController) PostsPage(c *gin.Context) {
 	uid, _, ok := common.GetGinUser(c)
 	if !ok {
-		c.Redirect(http.StatusFound, "/auth/login")
+		common.RedirectToLogin(c)
 		return
 	}
 
@@ -96,7 +96,7 @@ func (ctrl *StudioController) PostsPage(c *gin.Context) {
 func (ctrl *StudioController) DraftsPage(c *gin.Context) {
 	uid, _, ok := common.GetGinUser(c)
 	if !ok {
-		c.Redirect(http.StatusFound, "/auth/login")
+		common.RedirectToLogin(c)
 		return
 	}
 
@@ -131,7 +131,7 @@ func (ctrl *StudioController) DraftsPage(c *gin.Context) {
 func (ctrl *StudioController) WritePage(c *gin.Context) {
 	uid, _, ok := common.GetGinUser(c)
 	if !ok {
-		c.Redirect(http.StatusFound, "/auth/login")
+		common.RedirectToLogin(c)
 		return
 	}
 
@@ -171,7 +171,7 @@ func (ctrl *StudioController) WritePage(c *gin.Context) {
 func (ctrl *StudioController) AnalyticsPage(c *gin.Context) {
 	uid, _, ok := common.GetGinUser(c)
 	if !ok {
-		c.Redirect(http.StatusFound, "/auth/login")
+		common.RedirectToLogin(c)
 		return
 	}