ci: add ESLint lint workflow with per-directory configs

Node.js env for server.js/worker/, browser env for public/.
All errors downgraded to warnings (empty blocks, inner declarations,
loose equality, useless escape, constant condition) for practical CI.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.eslintrc.json

@@ -0,0 +1,13 @@
+{
+    "env": { "node": true, "es2021": true },
+    "extends": "eslint:recommended",
+    "parserOptions": { "ecmaVersion": 2021, "sourceType": "commonjs" },
+    "rules": {
+        "no-unused-vars": "warn",
+        "no-empty": "warn",
+        "no-constant-condition": "warn",
+        "no-useless-escape": "warn",
+        "semi": ["error", "always"],
+        "eqeqeq": "warn"
+    }
+}

.gitea/workflows/lint.yml

@@ -0,0 +1,20 @@
+name: Lint
+
+on:
+  push:
+    branches: ["**"]
+  pull_request:
+    branches: ["**"]
+
+jobs:
+  js-lint:
+    name: JS (eslint)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install ESLint
+        run: npm install --save-dev eslint@8
+
+      - name: Run ESLint
+        run: npx eslint server.js public/ worker/

package.json

@@ -16,5 +16,8 @@
     "express-rate-limit": "^8.3.1",
     "mysql2": "^3.15.3",
     "ws": "^8.18.3"
+  },
+  "devDependencies": {
+    "eslint": "^8.57.1"
   }
 }

public/.eslintrc.json

@@ -0,0 +1,11 @@
+{
+    "env": { "browser": true, "es2021": true },
+    "parserOptions": { "ecmaVersion": 2021, "sourceType": "script" },
+    "rules": {
+        "no-unused-vars": "warn",
+        "no-empty": "warn",
+        "no-inner-declarations": "warn",
+        "semi": ["error", "always"],
+        "eqeqeq": "warn"
+    }
+}