Update dependencies (Svelte 5, Eslint 9) (#10)

* upgrade to svelte 5, eslint 9, vite 6, tailwind 4
* fix vitest config
* fix dark mode button cursor, dark mode text color

Author: ldgit

.eslintignore

@@ -0,0 +1,37 @@
+import globals from 'globals';
+import pluginJs from '@eslint/js';
+import tseslint from 'typescript-eslint';
+import eslintPluginSvelte from 'eslint-plugin-svelte';
+import svelteConfig from './svelte.config.js';
+import eslintConfigPrettier from 'eslint-config-prettier';
+import * as typescriptParser from '@typescript-eslint/parser';
+
+/** @type {import('eslint').Linter.Config[]} */
+export default [
+  { files: ['**/*.{js,mjs,cjs,ts}'] },
+  { languageOptions: { globals: globals.browser } },
+  pluginJs.configs.recommended,
+  ...tseslint.configs.recommended,
+  ...eslintPluginSvelte.configs['flat/recommended'],
+  eslintConfigPrettier,
+  {
+    ignores: ['dist/', 'node_modules/'],
+  },
+  {
+    files: ['**/*.svelte', '*.svelte'],
+    languageOptions: {
+      parserOptions: {
+        svelteConfig,
+        /**
+         * Need these options so eslint can correctly check typescript syntax in .svelte files.
+         *
+         * @see https://sveltejs.github.io/eslint-plugin-svelte/user-guide/#parser-configuration
+         */
+        parser: typescriptParser,
+        project: './tsconfig.json',
+        extraFileExtensions: ['.svelte'],
+      },
+    },
+  },
+  { rules: { '@typescript-eslint/no-unused-vars': 'warn' } },
+];