frontend: add and fix linting

Author: ffreddow

frontend/.eslintignore

@@ -0,0 +1,10 @@
+dist/
+node_modules/
+target/
+pkg/
+*.config.ts
+*.config.js
+test-results/
+playwright-report/
+coverage/
+.vscode/

frontend/.eslintrc.json

@@ -0,0 +1,56 @@
+{
+  "env": {
+    "browser": true,
+    "es2021": true,
+    "node": true,
+    "worker": true,
+    "serviceworker": true
+  },
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+    "preact"
+  ],
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": "latest",
+    "sourceType": "module",
+    "ecmaFeatures": {
+      "jsx": true
+    },
+    "project": "./tsconfig.json"
+  },
+  "plugins": [
+    "@typescript-eslint"
+  ],
+  "rules": {
+    "@typescript-eslint/no-unused-vars": ["error", { "argsIgnorePattern": "^_" }],
+    "@typescript-eslint/no-explicit-any": "warn",
+    "@typescript-eslint/no-empty-function": "warn",
+    "@typescript-eslint/no-non-null-assertion": "warn",
+    "@typescript-eslint/no-this-alias": "off",
+    "@typescript-eslint/no-empty-object-type": "off",
+    "react-hooks/rules-of-hooks": "off",
+    "react-hooks/exhaustive-deps": "off",
+    "no-undef": "off",
+    "no-unused-vars": "off",
+    "quote-props": "off",
+    "no-duplicate-imports": "error",
+    "no-case-declarations": "off",
+    "no-undef-init": "warn",
+    "prefer-const": "warn",
+    "prefer-template": "warn",
+    "no-else-return": "warn",
+    "no-async-promise-executor": "off"
+  },
+  "ignorePatterns": [
+    "dist/",
+    "node_modules/",
+    "target/",
+    "pkg/",
+    "*.config.ts",
+    "*.config.js",
+    "test-results/",
+    "playwright-report/"
+  ]
+}