lint: prepare eslint

package.json

@@ -3,6 +3,9 @@
   "version": "0.7.1",
   "description": "Adds item pricing to the Team Fortress 2 wiki",
   "devDependencies": {
+    "@eslint/css": "^0.7.0",
+    "@eslint/js": "^9.25.1",
+    "@eslint/json": "^0.12.0",
     "@happy-dom/global-registrator": "^17.4.4",
     "@types/firefox-webext-browser": "^120.0.4",
     "@types/greasemonkey": "^4.0.7",
@@ -12,10 +15,13 @@
     "buffer": "^6.0.3",
     "bun-types": "^1.2.5",
     "copy-webpack-plugin": "^12.0.2",
+    "eslint": "^9.25.1",
+    "globals": "^16.0.0",
     "path-browserify": "^1.0.1",
     "raw-loader": "^4.0.2",
     "tf2-static-schema": "^1.74.0",
     "ts-loader": "^9.5.1",
+    "typescript-eslint": "^8.31.0",
     "webpack": "^5.94.0",
     "webpack-cli": "^5.1.4"
   },

src/eslint.config.mjs

@@ -0,0 +1,17 @@
+import js from "@eslint/js";
+import globals from "globals";
+import tseslint from "typescript-eslint";
+import json from "@eslint/json";
+import css from "@eslint/css";
+import { defineConfig } from "eslint/config";
+
+
+export default defineConfig([
+  { ignores: ["**/GM_fetch/**/*.js"] },
+  { files: ["**/*.{js,mjs,cjs,ts}"], plugins: { js }, extends: ["js/recommended"] },
+  { files: ["**/*.{js,mjs,cjs,ts}"], languageOptions: { globals: globals.browser } },
+  tseslint.configs.recommended,
+  { files: ["**/*.json"], plugins: { json }, language: "json/json", extends: ["json/recommended"] },
+  { files: ["**/*.jsonc"], plugins: { json }, language: "json/jsonc", extends: ["json/recommended"] },
+  { files: ["**/*.css"], plugins: { css }, language: "css/css", extends: ["css/recommended"] },
+]);