feat: Add comprehensive backend validation, toast notifications, and Tokyo Night theme

- Backend: Add server-side validation with go-playground/validator/v10
- Frontend: Add toast notifications for API errors with @zerodevx/svelte-toast
- UI: Complete Tokyo Night theme redesign with modern animations
- Docs: Update COMPLETE_DOCUMENTATION.md and README.md with all enhancements
- Validation: Email format, password strength, and input sanitization
- UX: Real-time error feedback, loading states, and responsive design

frontend/svelte.config.js

@@ -0,0 +1,16 @@
+import adapter from '@sveltejs/adapter-static';
+
+/** @type {import('@sveltejs/kit').Config} */
+const config = {
+	kit: {
+		adapter: adapter({
+			pages: 'build',
+			assets: 'build',
+			fallback: 'index.html',
+			precompress: false,
+			strict: true
+		})
+	}
+};
+
+export default config;