feat(landing): add strict ESLint + Prettier with pre-commit hooks (#50)

- Install ESLint 9 with flat config, TypeScript, Vue plugins
- Configure Prettier (140 char, 2-space indent, single quotes)
- Add pre-commit hooks via husky + lint-staged for auto-fix
- Rename components to multi-word (Countdown → CountdownTimer, etc.)
- Add explicit TypeScript prop/emit interfaces
- Remove all console.log statements
- Fix all ESLint violations and type errors
- Verify type-check, build, and HMR working

resolves #43

Co-authored-by: johba <johba@harb.eth>
Reviewed-on: https://codeberg.org/johba/harb/pulls/50

landing/eslint.config.js

@@ -0,0 +1,56 @@
+import pluginVue from 'eslint-plugin-vue';
+import vueTsEslintConfig from '@vue/eslint-config-typescript';
+import eslintConfigPrettier from 'eslint-config-prettier';
+
+export default [
+  {
+    name: 'app/files-to-lint',
+    files: ['**/*.{ts,mts,tsx,vue}'],
+  },
+  {
+    name: 'app/files-to-ignore',
+    ignores: ['**/dist/**', '**/dist-ssr/**', '**/coverage/**', '**/.vite/**', '**/.ponder/**', '**/node_modules/**'],
+  },
+  ...pluginVue.configs['flat/essential'],
+  ...vueTsEslintConfig(),
+  {
+    name: 'app/custom-rules',
+    rules: {
+      // TypeScript rules
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          argsIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          caughtErrorsIgnorePattern: '^_',
+        },
+      ],
+      '@typescript-eslint/no-explicit-any': 'error',
+
+      // Vue rules
+      'vue/multi-word-component-names': 'error',
+      'vue/no-unused-vars': 'error',
+      'vue/component-name-in-template-casing': ['error', 'PascalCase'],
+      'vue/require-default-prop': 'error',
+      'vue/require-prop-types': 'error',
+      'vue/html-indent': ['error', 2],
+      'vue/max-attributes-per-line': 'off', // Prettier handles this
+      'vue/singleline-html-element-content-newline': 'off', // Prettier handles this
+
+      // General rules
+      'no-console': 'error',
+      'max-len': ['error', { code: 140, ignoreUrls: true, ignoreStrings: true, ignoreTemplateLiterals: true }],
+      indent: ['error', 2, { SwitchCase: 1 }],
+
+      // Disable complexity rules
+      complexity: 'off',
+      'max-depth': 'off',
+      'max-nested-callbacks': 'off',
+      'max-lines': 'off',
+      'max-lines-per-function': 'off',
+      'max-params': 'off',
+      'max-statements': 'off',
+    },
+  },
+  eslintConfigPrettier,
+];