style(mcp): use errors.New for static error messages

Replaces fmt.Errorf with errors.New for static error message in resolveOwnerRepo. Marks unused context and args parameters with underscore in toolListLandingTemplates.

routers/api/v2/mcp_pages.go

@@ -4,6 +4,7 @@
 package v2
 
 import (
+	"errors"
 	"fmt"
 
 	repo_model "code.gitcaddy.com/server/v3/models/repo"
@@ -269,7 +270,7 @@ func toolGetLandingConfig(ctx *context.APIContext, args map[string]any) (any, er
 	return buildFullResponse(config), nil
 }
 
-func toolListLandingTemplates(ctx *context.APIContext, args map[string]any) (any, error) {
+func toolListLandingTemplates(_ *context.APIContext, _ map[string]any) (any, error) {
 	templates := pages_module.ValidTemplates()
 	displayNames := pages_module.TemplateDisplayNames()
 
@@ -647,7 +648,7 @@ func resolveOwnerRepo(args map[string]any) (string, string, error) {
 	owner, _ := args["owner"].(string)
 	repo, _ := args["repo"].(string)
 	if owner == "" || repo == "" {
-		return "", "", fmt.Errorf("owner and repo are required")
+		return "", "", errors.New("owner and repo are required")
 	}
 	return owner, repo, nil
 }