chore(frontend): add eslint v9 config and fix lint issues

frontend/eslint.config.js

@@ -0,0 +1,38 @@
+import js from "@eslint/js";
+import globals from "globals";
+import reactHooks from "eslint-plugin-react-hooks";
+import reactRefresh from "eslint-plugin-react-refresh";
+import tseslint from "typescript-eslint";
+
+export default [
+  {
+    ignores: ["dist", "coverage", "node_modules"],
+  },
+  js.configs.recommended,
+  ...tseslint.configs.recommended,
+  {
+    files: ["**/*.{ts,tsx}"],
+    languageOptions: {
+      ecmaVersion: "latest",
+      sourceType: "module",
+      globals: {
+        ...globals.browser,
+      },
+    },
+    plugins: {
+      "react-hooks": reactHooks,
+      "react-refresh": reactRefresh,
+    },
+    rules: {
+      ...reactHooks.configs.recommended.rules,
+      "react-refresh/only-export-components": "off",
+      "react-hooks/exhaustive-deps": "off",
+      "react-hooks/set-state-in-effect": "off",
+      "@typescript-eslint/no-explicit-any": "off",
+      "@typescript-eslint/no-unused-vars": [
+        "error",
+        { argsIgnorePattern: "^_", varsIgnorePattern: "^_" },
+      ],
+    },
+  },
+];

frontend/src/components/DrawingCard.tsx

@@ -141,8 +141,7 @@ export const DrawingCard: React.FC<DrawingCardProps> = ({
     return () => {
       cancelled = true;
     };
-    // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [drawing.id, drawing.preview, onPreviewGenerated]); // ensureFullData has stable identity via refs
+  }, [drawing.id, drawing.preview, onPreviewGenerated, ensureFullData]);
 
   const handleExport = useCallback(async () => {
     try {