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.

vercel.json

@@ -1,36 +1,36 @@
 {
-  "$schema": "https://openapi.vercel.sh/vercel.json",
-  "headers": [
-    {
-      "source": "/(.*)",
-      "headers": [
+    "$schema": "https://openapi.vercel.sh/vercel.json",
+    "headers": [
         {
-          "key": "X-Frame-Options",
-          "value": "DENY"
-        },
-        {
-          "key": "X-Content-Type-Options",
-          "value": "nosniff"
-        },
-        {
-          "key": "Referrer-Policy",
-          "value": "strict-origin"
-        },
-        {
-          "key": "Strict-Transport-Security",
-          "value": "max-age=31536000"
-        },
-        {
-          "key": "Permissions-Policy",
-          "value": "camera=(), microphone=(), payment=(), usb=(), geolocation=(self)"
+            "source": "/(.*)",
+            "headers": [
+                {
+                    "key": "X-Frame-Options",
+                    "value": "DENY"
+                },
+                {
+                    "key": "X-Content-Type-Options",
+                    "value": "nosniff"
+                },
+                {
+                    "key": "Referrer-Policy",
+                    "value": "strict-origin"
+                },
+                {
+                    "key": "Strict-Transport-Security",
+                    "value": "max-age=31536000"
+                },
+                {
+                    "key": "Permissions-Policy",
+                    "value": "camera=(), microphone=(), payment=(), usb=(), geolocation=(self)"
+                }
+            ]
         }
-      ]
-    }
-  ],
-  "rewrites": [
-    {
-      "source": "/(.*)",
-      "destination": "/index.html"
-    }
-  ]
+    ],
+    "rewrites": [
+        {
+            "source": "/(.*)",
+            "destination": "/index.html"
+        }
+    ]
 }