feat(sandbox): implement cross-platform support with Windows fallback

- Add conditional compilation for Unix-specific gaol sandbox functionality
- Implement Windows-compatible SandboxExecutor with no-op sandboxing
- Update ProfileBuilder to handle both Unix and Windows platforms
- Add platform-specific dependency declaration for gaol crate
- Modify agent and claude commands to use appropriate sandbox implementation
- Update test modules with conditional compilation for Unix-only tests
- Ensure graceful degradation on Windows with logging warnings

This change enables the application to build and run on Windows while
maintaining full sandbox security on Unix-like systems.

src-tauri/tests/sandbox_tests.rs

@@ -2,7 +2,9 @@
 //! 
 //! This file integrates all the sandbox test modules and provides
 //! a central location for running the comprehensive test suite.
-#[path = "sandbox/mod.rs"]
+#![allow(dead_code)]
+
+#[cfg(unix)]
 mod sandbox;
 
 // Re-export test modules to make them discoverable