feat: Enhance validation and permissions handling across controllers

- Added `ValidatedJson` extractor for automatic JSON validation in `events_controller.rs`, `testimonials_controller.rs`, `mentors_controller.rs`, `gacha_items_controller.rs`, and `hackathon_controller.rs`.
- Replaced manual permission checks with `require_permissions!` and `require_auth!` macros in relevant controllers to streamline permission handling.
- Introduced `sanitization` utilities in `sanitization.rs` for improved input sanitization.
- Added `permission_macros.rs` to encapsulate permission checking logic and reduce boilerplate.
- Updated dependencies in `Cargo.toml` to include `serde_json` and `validator`.
- Implemented error handling improvements in `notification_service.rs` for better response management.

imphnen-libs/src/axum/mod.rs

@@ -3,12 +3,16 @@
 //! This module provides utilities for initializing and running an Axum web server
 //! with SurrealDB connections for both WebSocket and in-memory databases.
 
+pub mod validated_json;
+
 use crate::{surrealdb_init_mem, surrealdb_init_ws, SurrealMemClient, SurrealWsClient};
 use axum::{Router, serve};
 use std::{future::Future, net::SocketAddr};
 use tokio::net::TcpListener;
 use crate::environment::ENV;
 
+pub use validated_json::ValidatedJson;
+
 /// Initialize and start the Axum server with SurrealDB connections.
 ///
 /// This function sets up both WebSocket and in-memory SurrealDB connections,