another step just a little remaining

client/eslint.config.mjs

@@ -0,0 +1,37 @@
+// Flat ESLint config (ESLint 10 / Next.js 16).
+//
+// `next lint` was removed in Next 16, so linting runs through the ESLint CLI
+// directly: `npm run lint`. The eslint-config-next package (v16) ships a
+// ready-made flat-config array that wires up the Next core-web-vitals rules,
+// the TypeScript rules, react / react-hooks / jsx-a11y / import plugins and the
+// TypeScript parser — so we just spread it and layer our project rules on top.
+
+import next from 'eslint-config-next';
+import prettier from 'eslint-config-prettier/flat';
+
+/** @type {import('eslint').Linter.Config[]} */
+const config = [
+  // Things ESLint should never look at.
+  {
+    ignores: ['.next/**', 'out/**', 'coverage/**', 'node_modules/**', 'next-env.d.ts'],
+  },
+
+  // Next.js + TypeScript + React + import/a11y rule sets.
+  ...next,
+
+  // Turn off every stylistic rule that would fight Prettier. Keep this last
+  // among the rule-providing entries so it wins. Formatting is owned by
+  // Prettier (`npm run format`), never by ESLint.
+  prettier,
+
+  // Project-specific rule overrides go here, e.g.:
+  //   { rules: { 'react/jsx-key': 'error' } }
+  //
+  // NOTE: `import/no-cycle` is intentionally NOT enabled. On this toolchain the
+  // eslint-plugin-import TypeScript resolver bundled by eslint-config-next 16
+  // throws "invalid interface loaded as resolver" for that rule, and it cannot
+  // follow the `@/*` path alias to trace cycles anyway. Re-add it once the
+  // import-resolver-typescript interface is compatible.
+];
+
+export default config;