add ESLint config and install missing lint dependencies

next lint was failing in CI because no ESLint config existed, causing it
to prompt interactively and exit with code 1. Adds eslint.config.mjs with
next/core-web-vitals + next/typescript rules. Pre-existing style violations
(unescaped entities, explicit any, a-vs-Link) are downgraded to warnings so
CI gates on new errors without blocking on legacy code.

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

Author: nchalla3

eslint.config.mjs

@@ -0,0 +1,26 @@
+import { dirname } from "path";
+import { fileURLToPath } from "url";
+import { FlatCompat } from "@eslint/eslintrc";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+});
+
+const eslintConfig = [
+  ...compat.extends("next/core-web-vitals", "next/typescript"),
+  {
+    // Downgrade pre-existing style violations to warnings so CI doesn't block
+    // on legacy code. These are not runtime bugs — the site functions correctly
+    // with them present. Tighten these back to "error" once the backlog is cleared.
+    rules: {
+      "react/no-unescaped-entities": "warn",
+      "@typescript-eslint/no-explicit-any": "warn",
+      "@next/next/no-html-link-for-pages": "warn",
+    },
+  },
+];
+
+export default eslintConfig;