feat: add CSP header (#908)

Co-authored-by: Alessandro (Ale) Segala <43508+ItalyPaleAle@users.noreply.github.com>

backend/internal/controller/version_controller.go

@@ -0,0 +1,40 @@
+package controller
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/pocket-id/pocket-id/backend/internal/service"
+	"github.com/pocket-id/pocket-id/backend/internal/utils"
+)
+
+// NewVersionController registers version-related routes.
+func NewVersionController(group *gin.RouterGroup, versionService *service.VersionService) {
+	vc := &VersionController{versionService: versionService}
+	group.GET("/version/latest", vc.getLatestVersionHandler)
+}
+
+type VersionController struct {
+	versionService *service.VersionService
+}
+
+// getLatestVersionHandler godoc
+// @Summary Get latest available version of Pocket ID
+// @Tags Version
+// @Produce json
+// @Success 200 {object} map[string]string "Latest version information"
+// @Router /api/version/latest [get]
+func (vc *VersionController) getLatestVersionHandler(c *gin.Context) {
+	tag, err := vc.versionService.GetLatestVersion(c.Request.Context())
+	if err != nil {
+		_ = c.Error(err)
+		return
+	}
+
+	utils.SetCacheControlHeader(c, 5*time.Minute, 15*time.Minute)
+
+	c.JSON(http.StatusOK, gin.H{
+		"latestVersion": tag,
+	})
+}