feat: add i18n labels for frame step shortcuts (en, es, zh-CN)

src/i18n/locales/en/shortcuts.json

@@ -29,6 +29,8 @@
 		"cycleAnnotationsBackward": "Cycle Annotations Backward",
 		"deleteSelectedAlt": "Delete Selected (alt)",
 		"panTimeline": "Pan Timeline",
-		"zoomTimeline": "Zoom Timeline"
+		"zoomTimeline": "Zoom Timeline",
+		"frameBack": "Frame Back",
+		"frameForward": "Frame Forward"
 	}
 }

src/i18n/locales/es/shortcuts.json

@@ -29,6 +29,8 @@
 		"cycleAnnotationsBackward": "Recorrer anotaciones hacia atrás",
 		"deleteSelectedAlt": "Eliminar seleccionado (alt)",
 		"panTimeline": "Desplazar línea de tiempo",
-		"zoomTimeline": "Zoom en línea de tiempo"
+		"zoomTimeline": "Zoom en línea de tiempo",
+		"frameBack": "Fotograma anterior",
+		"frameForward": "Fotograma siguiente"
 	}
 }

src/i18n/locales/zh-CN/shortcuts.json

@@ -29,6 +29,8 @@
 		"cycleAnnotationsBackward": "向后切换标注",
 		"deleteSelectedAlt": "删除所选（替代）",
 		"panTimeline": "平移时间轴",
-		"zoomTimeline": "缩放时间轴"
+		"zoomTimeline": "缩放时间轴",
+		"frameBack": "上一帧",
+		"frameForward": "下一帧"
 	}
 }