chore: standardize on ParsedCommand from codex_protocol (#5218)

Note these two types were identical, so it seems clear to standardize on the one in `codex_protocol` and eliminate the `Into` stuff.

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[//]: # (BEGIN SAPLING FOOTER)
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* #5222
* __->__ #5218

codex-rs/core/src/codex.rs

@@ -882,10 +882,7 @@ impl Session {
                 call_id,
                 command: command_for_display.clone(),
                 cwd,
-                parsed_cmd: parse_command(&command_for_display)
-                    .into_iter()
-                    .map(Into::into)
-                    .collect(),
+                parsed_cmd: parse_command(&command_for_display),
             }),
         };
         let event = Event {