feat: add update command to CLI, relay, and client

crates/common/src/protocol.rs

@@ -108,6 +108,8 @@ pub enum ServerMessage {
     ClipboardGetRequest { request_id: Uuid },
     /// Set the contents of the client's clipboard
     ClipboardSetRequest { request_id: Uuid, text: String },
+    /// Request client to self-update and restart
+    UpdateRequest { request_id: Uuid },
 }
 
 /// Messages sent from the client to the relay server
@@ -163,6 +165,12 @@ pub enum ClientMessage {
     ClipboardGetResponse { request_id: Uuid, text: String },
     /// Response to a prompt request
     PromptResponse { request_id: Uuid, answer: String },
+    /// Response to an update request
+    UpdateResponse {
+        request_id: Uuid,
+        success: bool,
+        message: String,
+    },
 }
 
 #[cfg(test)]