feat(eslint): add eslint flat config

.eslint/javascript.ts

@@ -0,0 +1,35 @@
+import type { Linter } from "eslint";
+import { javascriptFiles } from "./shared";
+
+export const javascriptConfig: Linter.Config = {
+  name: "eslint/javascript",
+  files: javascriptFiles,
+  languageOptions: {
+    ecmaVersion: "latest",
+    sourceType: "module",
+    parserOptions: {
+      ecmaFeatures: {
+        jsx: true,
+      },
+    },
+  },
+  rules: {
+    "no-unused-vars": [
+      "error",
+      {
+        argsIgnorePattern: "^_",
+        varsIgnorePattern: "^_",
+        ignoreRestSiblings: true,
+      },
+    ],
+    "no-console": ["warn", { allow: ["warn", "error"] }],
+    "no-debugger": "error",
+    "prefer-const": "error",
+    "no-var": "error",
+    "object-shorthand": "error",
+    "prefer-template": "error",
+    curly: ["error", "all"],
+    eqeqeq: ["error", "always"],
+    "no-implicit-coercion": "error",
+  },
+};