feat(core): Define AppMode enum and add to AppState

crates/app/cli/src/state.rs

@@ -1,12 +1,27 @@
 use std::sync::Arc;
 use tokio::sync::Mutex;
 use llm_core::ChatMessage;
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum AppMode {
+    Normal,
+    Plan,
+    AcceptAll,
+}
+
+impl Default for AppMode {
+    fn default() -> Self {
+        Self::Normal
+    }
+}
 
 /// Shared application state
 #[derive(Debug, Default)]
 pub struct AppState {
     pub messages: Vec<ChatMessage>,
     pub running: bool,
+    pub mode: AppMode,
 }
 
 impl AppState {
@@ -14,6 +29,7 @@ impl AppState {
         Self {
             messages: Vec::new(),
             running: true,
+            mode: AppMode::Normal,
         }
     }