feat(eslint): add eslint flat config

.eslint/astro.ts

@@ -0,0 +1,28 @@
+import type { Linter } from "eslint";
+// @ts-expect-error - no types available
+import jsxA11y from "eslint-plugin-jsx-a11y";
+import { astroFiles } from "./shared";
+
+export const astroConfig: Linter.Config = {
+  name: "eslint/astro",
+  files: astroFiles,
+  plugins: {
+    "jsx-a11y": jsxA11y,
+  },
+  rules: {
+    // Astro specific adjustments
+    "@typescript-eslint/no-unused-vars": "off", // Astro components can have unused props
+    "import/no-unresolved": "off",
+    "no-undef": "off", // Astro has global variables like Astro
+
+    // A11y rules for Astro
+    "jsx-a11y/alt-text": "error",
+    "jsx-a11y/anchor-has-content": "error",
+    "jsx-a11y/anchor-is-valid": "error",
+    "jsx-a11y/click-events-have-key-events": "error",
+    "jsx-a11y/interactive-supports-focus": "error",
+    "jsx-a11y/no-redundant-roles": "error",
+    "jsx-a11y/img-redundant-alt": "error",
+    "jsx-a11y/no-access-key": "error",
+  },
+};