ci: add ESLint flat config with astro + jsx-a11y

Pin eslint@9 (jsx-a11y peer) and add eslint-plugin-astro + eslint-plugin-jsx-a11y + typescript-eslint as devDeps.

eslint.config.js wires:
- @eslint/js recommended and typescript-eslint recommended for general .ts/.mjs.
- astro flat/jsx-a11y-recommended for .astro files, registering the jsx-a11y plugin explicitly.
- project-specific tweaks: drop jsx-a11y/anchor-is-valid (noisy on Astro links), warn on click-events-have-key-events and no-static-element-interactions, allow any in scripts/tests, ignore env.d.ts triple-slash ref (Astro convention).

Scripts: lint and lint:fix. prebuild now also runs lint, so the same chain guards a11y regressions as type and build errors.

CI workflow gains a lint step between check and build. 0 errors, 16/16 e2e still pass.

.gitea/workflows/ci.yml

@@ -42,6 +42,9 @@ jobs:
       - name: Typecheck (astro check)
         run: pnpm run check
 
+      - name: Lint
+        run: pnpm run lint
+
       - name: Build
         run: pnpm run build
 

eslint.config.js

@@ -0,0 +1,53 @@
+import js from '@eslint/js';
+import tseslint from 'typescript-eslint';
+import astro from 'eslint-plugin-astro';
+import jsxA11y from 'eslint-plugin-jsx-a11y';
+
+export default [
+  {
+    ignores: ['dist/**', '.astro/**', 'node_modules/**', 'playwright-report/**', 'test-results/**', 'public/**'],
+  },
+  js.configs.recommended,
+  ...tseslint.configs.recommended,
+  ...astro.configs['flat/jsx-a11y-recommended'],
+  {
+    files: ['**/*.{ts,tsx,js,jsx,mjs}'],
+    languageOptions: {
+      ecmaVersion: 2024,
+      sourceType: 'module',
+    },
+  },
+  {
+    files: ['**/*.astro'],
+    plugins: {
+      astro,
+      'jsx-a11y': jsxA11y,
+    },
+    rules: {
+      ...astro.configs.recommended.rules,
+      'jsx-a11y/anchor-is-valid': 'off',
+      'jsx-a11y/click-events-have-key-events': 'warn',
+      'jsx-a11y/no-static-element-interactions': 'warn',
+    },
+  },
+  {
+    files: ['scripts/**/*.{mjs,js}', 'tests/**/*.{ts,mts}'],
+    languageOptions: {
+      globals: {
+        console: 'readonly',
+        process: 'readonly',
+        Buffer: 'readonly',
+        URL: 'readonly',
+      },
+    },
+    rules: {
+      '@typescript-eslint/no-explicit-any': 'off',
+    },
+  },
+  {
+    files: ['src/env.d.ts'],
+    rules: {
+      '@typescript-eslint/triple-slash-reference': 'off',
+    },
+  },
+];

package.json

@@ -8,11 +8,13 @@
   },
   "scripts": {
     "dev": "astro dev",
-    "prebuild": "node scripts/build-og-image.mjs && astro check",
+    "prebuild": "node scripts/build-og-image.mjs && astro check && eslint .",
     "build": "astro build",
     "preview": "astro preview",
     "check": "astro check",
     "check:watch": "astro check --watch",
+    "lint": "eslint .",
+    "lint:fix": "eslint . --fix",
     "pretest:e2e": "astro check && astro build",
     "test:e2e": "playwright test",
     "test:e2e:install": "playwright install --with-deps chromium"
@@ -29,10 +31,15 @@
   "devDependencies": {
     "@astrojs/check": "^0.9.4",
     "@axe-core/playwright": "^4.12.1",
+    "@eslint/js": "^10.0.1",
     "@playwright/test": "^1.62.0",
     "@types/leaflet": "^1.9.12",
     "@types/pg": "^8.11.10",
     "axe-core": "^4.12.1",
-    "typescript": "^5.6.3"
+    "eslint": "^9.39.5",
+    "eslint-plugin-astro": "^3.0.1",
+    "eslint-plugin-jsx-a11y": "^6.10.2",
+    "typescript": "^5.6.3",
+    "typescript-eslint": "^8.65.0"
   }
 }