perf: build backend with swc (#9463)

* feat: build backend with swc

* fix: swc build target

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

packages/backend/.swcrc

@@ -9,7 +9,17 @@
     "transform": {
       "legacyDecorator": true,
       "decoratorMetadata": true
-    }
+    },
+		"experimental": {
+			"keepImportAssertions": true
+		},
+		"baseUrl": ".",
+		"paths": {
+			"@/*": [
+				"./src/*"
+			]
+		},
+		"target": "es2021"
   },
   "minify": false
 }