Use UserTurn for app-server turn start

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/src/codex.rs

@@ -1075,6 +1075,7 @@ impl SessionConfiguration {
             cwd: self.cwd.clone(),
             ephemeral: self.original_config_do_not_use.ephemeral,
             reasoning_effort: self.collaboration_mode.reasoning_effort(),
+            collaboration_mode: self.collaboration_mode.clone(),
             personality: self.personality,
             session_source: self.session_source.clone(),
         }

codex-rs/core/src/codex_thread.rs

@@ -39,6 +39,7 @@ pub struct ThreadConfigSnapshot {
     pub cwd: PathBuf,
     pub ephemeral: bool,
     pub reasoning_effort: Option<ReasoningEffort>,
+    pub collaboration_mode: codex_protocol::config_types::CollaborationMode,
     pub personality: Option<Personality>,
     pub session_source: SessionSource,
 }