fix: resolve TypeScript and Rust build errors and warnings

- Fixed TypeScript errors in ClaudeCodeSession.tsx:
  - Removed unused imports (Square, PreviewPromptDialog, etc.)
  - Removed unused handleOpenPreview function
  - Fixed unused detectedUrl state variable
- Fixed TypeScript error in StreamMessage.tsx:
  - Removed unused useMemo import
- Fixed TypeScript errors in ToolWidgets.tsx:
  - Prefixed unused result props with underscore in multiple widgets
- Fixed Rust warnings:
  - Removed unused imports in commands modules
  - Prefixed unused variables with underscore
  - Added #[allow(dead_code)] for API methods intended for future use

Closes #31
Closes #23
Closes #21
Closes #22

src-tauri/src/checkpoint/mod.rs

@@ -244,11 +244,13 @@ impl CheckpointPaths {
         self.checkpoint_dir(checkpoint_id).join("messages.jsonl")
     }
     
+    #[allow(dead_code)]
     pub fn file_snapshot_path(&self, _checkpoint_id: &str, file_hash: &str) -> PathBuf {
         // In content-addressable storage, files are stored by hash in the content pool
         self.files_dir.join("content_pool").join(file_hash)
     }
     
+    #[allow(dead_code)]
     pub fn file_reference_path(&self, checkpoint_id: &str, safe_filename: &str) -> PathBuf {
         // References are stored per checkpoint
         self.files_dir.join("refs").join(checkpoint_id).join(format!("{}.json", safe_filename))

src-tauri/src/checkpoint/state.rs

@@ -87,6 +87,7 @@ impl CheckpointState {
     /// Gets an existing CheckpointManager for a session
     /// 
     /// Returns None if no manager exists for the session
+    #[allow(dead_code)]
     pub async fn get_manager(&self, session_id: &str) -> Option<Arc<CheckpointManager>> {
         let managers = self.managers.read().await;
         managers.get(session_id).map(Arc::clone)
@@ -103,6 +104,7 @@ impl CheckpointState {
     /// Clears all managers
     /// 
     /// This is useful for cleanup during application shutdown
+    #[allow(dead_code)]
     pub async fn clear_all(&self) {
         let mut managers = self.managers.write().await;
         managers.clear();
@@ -121,11 +123,13 @@ impl CheckpointState {
     }
     
     /// Checks if a session has an active manager
+    #[allow(dead_code)]
     pub async fn has_active_manager(&self, session_id: &str) -> bool {
         self.get_manager(session_id).await.is_some()
     }
     
     /// Clears all managers and returns the count that were cleared
+    #[allow(dead_code)]
     pub async fn clear_all_and_count(&self) -> usize {
         let count = self.active_count().await;
         self.clear_all().await;