Rename employee-tracking-backend to purenotify_backend and add OFFLINE

mode

- Rename crate and update dependencies to newer versions - Add OFFLINE
runtime mode for loopback-only server without DB - Refactor state
handling with typed Axum routers and state injection - Rename mongodb
module to mongo and fix imports accordingly - Update Cargo.lock with
updated and removed dependencies - Remove no-auth feature and related
code - Simplify health and user routes to generic state parameter Rename
backend to purenotify_backend and add OFFLINE mode

Use OFFLINE env var to run server without DB, binding to loopback only.
Rename mongodb module to mongo and update dependencies. Update
dependencies and fix router state handling.

src/config.rs

@@ -4,7 +4,6 @@ use std::env;
 use std::net::SocketAddr;
 use std::str::FromStr;
 
-#[cfg(feature = "no-auth")]
 use tracing::error;
 
 #[derive(Debug, Clone)]
@@ -22,7 +21,6 @@ impl Config {
         let bind_address = SocketAddr::from_str(&bind_address_str)
             .map_err(|e| format!("Invalid BIND_ADDRESS: {}", e))?;
 
-        #[cfg(feature = "no-auth")]
         if bind_address.ip() != std::net::IpAddr::from([127, 0, 0, 1]) {
             error!("In no-auth mode, BIND_ADDRESS must be 127.0.0.1");
             return Err("In no-auth mode, BIND_ADDRESS must be 127.0.0.1".to_string());