Add explicit prefix-approval decision and wire it through execpolicy/UI snapshots

codex-rs/protocol/src/protocol.rs

@@ -1657,6 +1657,10 @@ pub enum ReviewDecision {
     /// User has approved this command and the agent should execute it.
     Approved,
 
+    /// User has approved this command and wants to add the command prefix to
+    /// the execpolicy allow list so future matching commands are permitted.
+    ApprovedAllowPrefix,
+
     /// User has approved this command and wants to automatically approve any
     /// future identical instances (`command` and `cwd` match exactly) for the
     /// remainder of the session.