Remove App implementation: delete TUI application logic, event handling, and related structures.

crates/owlen-tui/src/code_app.rs

@@ -1,8 +1,9 @@
 use anyhow::Result;
 use owlen_core::session::SessionController;
+use owlen_core::ui::{AppState, InputMode};
 use tokio::sync::mpsc;
 
-use crate::chat_app::{AppState, ChatApp, InputMode, SessionEvent};
+use crate::chat_app::{ChatApp, SessionEvent};
 use crate::events::Event;
 
 const DEFAULT_SYSTEM_PROMPT: &str =