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/src/commands/agents.rs

@@ -996,12 +996,20 @@ pub async fn execute_agent(
                     Ok(build_result) => {
                         
                         // Create the enhanced sandbox executor
+                        #[cfg(unix)]
                         let executor = crate::sandbox::executor::SandboxExecutor::new_with_serialization(
                             build_result.profile,
                             project_path_buf.clone(),
                             build_result.serialized
                         );
                         
+                        #[cfg(not(unix))]
+                        let executor = crate::sandbox::executor::SandboxExecutor::new_with_serialization(
+                            (),
+                            project_path_buf.clone(),
+                            build_result.serialized
+                        );
+                        
                         // Prepare the sandboxed command
                         let args = vec![
                             "-p", &task,