(feat): rename example-usage to just example

(feat): add the example's web-client dist folder to a gitignore
(fix): format issues
(fix): a lot of duplicate code

example/client/src/auth.rs

@@ -0,0 +1,52 @@
+use std::fs;
+
+use mtp::client::{ClientConfig, MTPClient, MTPConnection};
+use mtp::crypto::{Ed25519Signer, Keyring, MlDsaSigner, PublicKeyBundle};
+
+pub async fn connect_or_register(
+    mut config: ClientConfig,
+    host_public_key: PublicKeyBundle,
+    client_key_path: &str,
+) -> Result<(MTPConnection, Keyring), Box<dyn std::error::Error>> {
+    if let Ok(data) = fs::read_to_string(client_key_path) {
+        let json: serde_json::Value = serde_json::from_str(&data)?;
+        let client_id = json["client_id"].as_u64().expect("Invalid client_id");
+        let keyring = Keyring::from_bytes(&hex::decode(
+            json["keyring"].as_str().expect("Missing keyring"),
+        )?)?;
+
+        println!("Loaded client keys (ID: {})", client_id);
+
+        config.client_id = client_id;
+        let conn = MTPClient::auth_connect(config, &keyring, &host_public_key).await?;
+        println!("Authenticated (version {})", conn.version);
+        Ok((conn, keyring))
+    } else {
+        println!("No existing keys found: registering new client");
+
+        let (_ed_signer, sig_sk, sig_pk) = Ed25519Signer::generate();
+        let (_pq_signer, sig_pq_sk, sig_pq_pk) = MlDsaSigner::generate();
+        let keyring = Keyring::new(
+            mtp::crypto::KemPublicKey::new(vec![]),
+            mtp::crypto::KemPrivateKey::new(vec![]),
+            sig_pq_pk,
+            sig_pq_sk,
+            sig_pk,
+            sig_sk,
+        );
+
+        let keyring_bytes = keyring.to_bytes();
+        let conn = MTPClient::auth_register(config, &keyring, &host_public_key).await?;
+        println!("Registered with ID: {}", conn.client_id);
+
+        let json = serde_json::json!({
+            "client_id": conn.client_id,
+            "keyring": hex::encode(&keyring_bytes),
+        });
+        fs::write(client_key_path, serde_json::to_string_pretty(&json)?)?;
+        println!("Saved client keys -> {client_key_path}");
+
+        let keyring = Keyring::from_bytes(&keyring_bytes)?;
+        Ok((conn, keyring))
+    }
+}