chore: 统一项目编辑器配置，移至仓库根目录

.editorconfig

@@ -0,0 +1,7 @@
+root = true
+
+[*]
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = true
+charset = utf-8

.gitattributes

@@ -0,0 +1 @@
+* text=auto eol=lf

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "files.eol": "\n"
+}

frontend/.vscode/extensions.json

@@ -1,3 +0,0 @@
-{
-  "recommendations": ["esbenp.prettier-vscode", "dbaeumer.vscode-eslint"]
-}

frontend/.vscode/settings.json

@@ -1,7 +0,0 @@
-{
-  "editor.formatOnSave": true,
-  "editor.defaultFormatter": "esbenp.prettier-vscode",
-  "editor.codeActionsOnSave": {
-    "source.fixAll.eslint": "explicit"
-  }
-}