refactor: organize features and standardize frontend tooling

Colocate feature views, components, stores, and upload logic; centralize shared map utilities without changing API behavior.

Add ESLint, Prettier, EditorConfig, and VS Code settings; standardize four-space indentation and document the project structure and checks.

Validation: npm run check, npm run build, and git diff --check.

.vscode/settings.json

@@ -0,0 +1,11 @@
+{
+    "editor.tabSize": 4,
+    "editor.insertSpaces": true,
+    "editor.detectIndentation": false,
+    "editor.defaultFormatter": "esbenp.prettier-vscode",
+    "editor.formatOnSave": true,
+    "editor.codeActionsOnSave": {
+        "source.fixAll.eslint": "explicit"
+    },
+    "eslint.validate": ["javascript", "typescript", "vue"]
+}