refactor(auth): implement token-based authentication with JWT parsing

- Replace authStore with tokenService for authentication management
- Add JWT parsing utility to extract user info from tokens
- Update login flow to use cookie-based token storage
- Modify logout to properly clear auth state and cookies
- Integrate user data into page context for SSR compatibility
- Remove deprecated authStore and related localStorage logic
- Add cookie constants for consistent token handling
- Implement server-side token validation in hooks
- Update HTTP client to use token from cookies instead of store
- Refactor error handling to use unified ApiError class
- Replace manual redirect logic with resolved paths
- Improve type safety with explicit user and auth interfaces
- Add toast notifications for login/logout feedback
- Remove unused sidebar store and related UI logic
- Migrate theme handling to use cookies and context
- Update icon definitions and component references
- Clean up legacy code and unused imports

src/lib/api/services/tokenService.ts

@@ -0,0 +1,45 @@
+import { api } from '$lib/api/httpClient';
+import type { ApiResult } from '$lib/types/api';
+import { authStore } from '$lib/stores/authStore';
+import { browser } from '$app/environment';
+
+export const tokenService = {
+	/**
+	 * Check if the current token is valid
+	 */
+	validateToken: async (): Promise<boolean> => {
+		if (!browser) return false;
+		
+		try {
+			const response = await api.get<null>('/auth/validate');
+			return response.code === 200;
+		} catch (error) {
+			console.error('Token validation failed:', error);
+			return false;
+		}
+	},
+	
+	/**
+	 * Refresh the current token
+	 */
+	refreshToken: async (): Promise<boolean> => {
+		if (!browser) return false;
+		
+		try {
+			const response = await api.post<{token: string, tokenHead: string}>('/auth/refresh', {});
+			if (response.code === 200 && response.data) {
+				// Update the auth store with new token
+				authStore.update(state => ({
+					...state,
+					token: response.data!.token,
+					tokenHead: response.data!.tokenHead
+				}));
+				return true;
+			}
+			return false;
+		} catch (error) {
+			console.error('Token refresh failed:', error);
+			return false;
+		}
+	}
+};