refactor: enhance security and performance in configuration and API routes

- Update Content Security Policy (CSP) in next.config.ts to avoid `unsafe-eval` in production, improving security against XSS attacks.
- Refactor API routes to enforce admin authentication and session validation, ensuring secure access to sensitive endpoints.
- Optimize analytics data retrieval by using database aggregation instead of loading all records into memory, improving performance and reducing memory usage.
- Implement session token creation and verification for better session management and security across the application.
- Enhance error handling and input validation in various API routes to ensure robustness and prevent potential issues.

app/editor/page.tsx

@@ -225,6 +225,7 @@ function EditorPageContent() {
         headers: {
           "Content-Type": "application/json",
           "x-admin-request": "true",
+          "x-session-token": sessionStorage.getItem("admin_session_token") || "",
         },
         body: JSON.stringify(saveData),
       });