Add new dependencies and implement TUN interface initialization

- Updated Cargo.toml to include `etherparse` and enable async feature for `tun-rs`.
- Added `ip_match_network` function in network module for IP matching.
- Implemented TUN interface initialization in `tun.rs`.
- Enhanced client handling in `client.rs` to support new features and improved message handling.
- Refactored router messages to use a structured `VpnPacket`.
- Updated settings for spell checking in VSCode.

src/tun.rs

@@ -0,0 +1,29 @@
+use anyhow::Result;
+use tun_rs::{AsyncDevice, DeviceBuilder};
+
+use crate::client::ClientCfg;
+
+pub async fn inti_tun_interface(config: &ClientCfg) -> Result<AsyncDevice> {
+    println!(
+        "Initializing TUN interface with name: {}, IP: {}/{}, MTU: {}",
+        config.interface_name,
+        config.interface_ip.addr(),
+        config.interface_ip.netmask(),
+        config.mtu
+    );
+    let device = match DeviceBuilder::new()
+        .name(&config.interface_name)
+        .ipv4(config.interface_ip.addr(), config.interface_ip.netmask(), None)
+        .mtu(config.mtu)
+        .build_async()
+    {
+        Ok(dev) => dev,
+        Err(e) => {
+            let msg = format!("Failed to create TUN interface: {:#}", e);
+            eprintln!("{}", msg);
+            return Err(anyhow::anyhow!(msg));
+        }
+    };
+
+    Ok(device)
+}