feat: add examples

examples/recover_ecdsa.rs

@@ -1,3 +1,12 @@
+use base64::Engine;
+use swift_secure_enclave_tool_rs::{recover_ecdsa_keypair, KeyPurpose};
+
 fn main() {
-    
-}
+    let args = std::env::args().collect::<Vec<_>>();
+    let private_key_representation = base64::engine::general_purpose::STANDARD
+        .decode(&args[1])
+        .unwrap();
+    let key_material =
+        recover_ecdsa_keypair(KeyPurpose::Signing, &private_key_representation).unwrap();
+    println!("{:?}", key_material)
+}