feat: add backup restore workflow

crates/geth-node/src/lib.rs

@@ -1,3 +1,4 @@
+pub mod backup;
 mod daemon;
 mod peer_client;
 mod runtime;
@@ -105,6 +106,8 @@ pub enum NodeError {
     Json(#[from] serde_json::Error),
     #[error("io error: {0}")]
     Io(#[from] std::io::Error),
+    #[error("backup error: {0}")]
+    Backup(String),
     #[error("invalid resource kind: {0}")]
     InvalidResourceKind(String),
     #[error("owner init requires --admin-key so the owner trust anchor is recorded")]