feat(catalog): class template editing

Templates were delete-and-recreate only. Adds PUT
/v1/catalog/class-templates/{id} across repository, service (sharing
the create-time validation), route, spec, and client; the classes tab
gets a pencil action that loads the row into the form with a
save/cancel affordance.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/api/server.go

@@ -998,6 +998,26 @@ func NewServer(cfg config.Config, pools *db.Pools) (*Server, error) {
 		}
 		c.JSON(http.StatusCreated, response)
 	})
+	protected.PUT("/catalog/class-templates/:templateID", func(c *gin.Context) {
+		var request domain.UpsertClassTemplateRequest
+		if err := c.ShouldBindJSON(&request); err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "invalid_request"})
+			return
+		}
+		response, err := catalogService.UpdateClassTemplate(c.Request.Context(), auth.PrincipalFromContext(c), c.Param("templateID"), request)
+		if err != nil {
+			status := http.StatusInternalServerError
+			switch {
+			case errors.Is(err, catalog.ErrTenantMembership), errors.Is(err, catalog.ErrClassTemplateNotFound):
+				status = http.StatusNotFound
+			case errors.Is(err, catalog.ErrInvalidInput):
+				status = http.StatusBadRequest
+			}
+			c.JSON(status, gin.H{"error": err.Error()})
+			return
+		}
+		c.JSON(http.StatusOK, response)
+	})
 	protected.DELETE("/catalog/class-templates/:templateID", func(c *gin.Context) {
 		err := catalogService.DeleteClassTemplate(c.Request.Context(), auth.PrincipalFromContext(c), c.Param("templateID"))
 		if err != nil {