feat: implement calculator app with pseudo-auth and CI/CD

- Calculator with full keyboard support and click interaction
- Pseudo-auth via localStorage (any login accepted)
- Dark theme (AntD ConfigProvider + custom styles)
- Responsive layout from 320px
- CI/CD: service.yaml + .drone.yml for deployment to test-calculator.vigdorov.ru

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

eslint.config.js

@@ -0,0 +1,23 @@
+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'
+import { defineConfig, globalIgnores } from 'eslint/config'
+
+export default defineConfig([
+  globalIgnores(['dist']),
+  {
+    files: ['**/*.{ts,tsx}'],
+    extends: [
+      js.configs.recommended,
+      tseslint.configs.recommended,
+      reactHooks.configs.flat.recommended,
+      reactRefresh.configs.vite,
+    ],
+    languageOptions: {
+      ecmaVersion: 2020,
+      globals: globals.browser,
+    },
+  },
+])