- Introduced `client.ts` and `server.ts` for structured environment variable management using `@t3-oss/env-nextjs`.
- Updated references to environment variables in various files to use the new `clientEnv` and `serverEnv` objects.
- Enhanced the `next.config.mjs` file to validate environment variables during build.
- Added new dependencies: `@t3-oss/env-nextjs` and `jiti` for improved environment handling.
- Cleaned up imports and ensured consistent usage of environment variables across the application.
