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/components/StreamMessage.tsx

@@ -1,4 +1,4 @@
-import React, { useState, useEffect, useMemo } from "react";
+import React, { useState, useEffect } from "react";
 import { 
   Terminal, 
   User,