fix: add Windows-compatible subprocess execution for CLI commands

- Create cross-platform subprocess utility with Windows shell=True support
- Update all CLI commands to use new subprocess utility instead of direct subprocess.run()
- Add comprehensive tests for Windows compatibility scenarios
- Fixes #3522: Access denied errors on Windows CLI execution

The core issue was that Windows with restrictive security policies blocks
subprocess execution when shell=False (the default). Using shell=True on
Windows allows commands to execute through the Windows shell, which
typically has the necessary permissions.

Files updated:
- src/crewai/cli/subprocess_utils.py (new utility)
- tests/cli/test_subprocess_utils.py (new tests)
- All CLI files that use subprocess.run(): run_crew.py, kickoff_flow.py,
  install_crew.py, train_crew.py, evaluate_crew.py, replay_from_task.py,
  plot_flow.py, tools/main.py, git.py

The solution maintains existing behavior on Unix-like systems while
providing Windows compatibility through platform detection.

Co-Authored-By: João <joao@crewai.com>

tests/cli/test_subprocess_utils.py

@@ -0,0 +1,141 @@
+import platform
+import subprocess
+from unittest import mock
+
+import pytest
+
+from crewai.cli.subprocess_utils import run_command
+
+
+class TestRunCommand:
+    """Test the cross-platform subprocess utility."""
+
+    @mock.patch("platform.system")
+    @mock.patch("subprocess.run")
+    def test_windows_uses_shell_true(self, mock_subprocess_run, mock_platform):
+        """Test that Windows uses shell=True with proper command conversion."""
+        mock_platform.return_value = "Windows"
+        mock_subprocess_run.return_value = subprocess.CompletedProcess(
+            args="uv run test", returncode=0
+        )
+
+        command = ["uv", "run", "test"]
+        run_command(command)
+
+        mock_subprocess_run.assert_called_once()
+        call_args = mock_subprocess_run.call_args
+        
+        assert call_args[1]["shell"] is True
+        assert isinstance(call_args[0][0], str)
+        assert "uv run test" in call_args[0][0]
+
+    @mock.patch("platform.system")
+    @mock.patch("subprocess.run")
+    def test_unix_uses_shell_false(self, mock_subprocess_run, mock_platform):
+        """Test that Unix-like systems use shell=False with list commands."""
+        mock_platform.return_value = "Linux"
+        mock_subprocess_run.return_value = subprocess.CompletedProcess(
+            args=["uv", "run", "test"], returncode=0
+        )
+
+        command = ["uv", "run", "test"]
+        run_command(command)
+
+        mock_subprocess_run.assert_called_once()
+        call_args = mock_subprocess_run.call_args
+        
+        assert call_args[1].get("shell", False) is False
+        assert call_args[0][0] == command
+
+    @mock.patch("platform.system")
+    @mock.patch("subprocess.run")
+    def test_windows_command_escaping(self, mock_subprocess_run, mock_platform):
+        """Test that Windows properly escapes command arguments."""
+        mock_platform.return_value = "Windows"
+        mock_subprocess_run.return_value = subprocess.CompletedProcess(
+            args="test", returncode=0
+        )
+
+        command = ["echo", "hello world", "test&special"]
+        run_command(command)
+
+        mock_subprocess_run.assert_called_once()
+        call_args = mock_subprocess_run.call_args
+        command_str = call_args[0][0]
+        
+        assert '"hello world"' in command_str or "'hello world'" in command_str
+
+    @mock.patch("platform.system")
+    @mock.patch("subprocess.run")
+    def test_error_handling_preserved(self, mock_subprocess_run, mock_platform):
+        """Test that CalledProcessError is properly raised."""
+        mock_platform.return_value = "Windows"
+        mock_subprocess_run.side_effect = subprocess.CalledProcessError(1, "test")
+
+        with pytest.raises(subprocess.CalledProcessError):
+            run_command(["test"], check=True)
+
+    @mock.patch("platform.system")
+    @mock.patch("subprocess.run")
+    def test_all_parameters_passed_through(self, mock_subprocess_run, mock_platform):
+        """Test that all subprocess parameters are properly passed through."""
+        mock_platform.return_value = "Linux"
+        mock_subprocess_run.return_value = subprocess.CompletedProcess(
+            args=["test"], returncode=0
+        )
+
+        run_command(
+            ["test"],
+            capture_output=True,
+            text=False,
+            check=False,
+            cwd="/tmp",
+            env={"TEST": "value"},
+            timeout=30
+        )
+
+        mock_subprocess_run.assert_called_once()
+        call_args = mock_subprocess_run.call_args
+        
+        assert call_args[1]["capture_output"] is True
+        assert call_args[1]["text"] is False
+        assert call_args[1]["check"] is False
+        assert call_args[1]["cwd"] == "/tmp"
+        assert call_args[1]["env"] == {"TEST": "value"}
+        assert call_args[1]["timeout"] == 30
+
+    @mock.patch("platform.system")
+    @mock.patch("subprocess.run")
+    def test_macos_uses_shell_false(self, mock_subprocess_run, mock_platform):
+        """Test that macOS uses shell=False with list commands."""
+        mock_platform.return_value = "Darwin"
+        mock_subprocess_run.return_value = subprocess.CompletedProcess(
+            args=["uv", "run", "test"], returncode=0
+        )
+
+        command = ["uv", "run", "test"]
+        run_command(command)
+
+        mock_subprocess_run.assert_called_once()
+        call_args = mock_subprocess_run.call_args
+        
+        assert call_args[1].get("shell", False) is False
+        assert call_args[0][0] == command
+
+    @mock.patch("platform.system")
+    @mock.patch("subprocess.run")
+    def test_windows_string_command_passthrough(self, mock_subprocess_run, mock_platform):
+        """Test that Windows passes through string commands unchanged."""
+        mock_platform.return_value = "Windows"
+        mock_subprocess_run.return_value = subprocess.CompletedProcess(
+            args="test command", returncode=0
+        )
+
+        command_str = "test command with spaces"
+        run_command(command_str)
+
+        mock_subprocess_run.assert_called_once()
+        call_args = mock_subprocess_run.call_args
+        
+        assert call_args[0][0] == command_str
+        assert call_args[1]["shell"] is True