Configure 3DOF acceptance tests to skip until feature is available

Co-authored-by: aZira371 <99824864+aZira371@users.noreply.github.com>

Author: Copilot

tests/acceptance/test_3dof_flight.py

@@ -11,14 +11,33 @@
 
 The tests use realistic rocket configurations and scenarios to ensure the
 robustness of the 3 DOF implementation.
+
+Note: These tests are designed for the 3 DOF feature implemented in issue #882.
+They will be skipped until PointMassMotor and PointMassRocket are available.
 """
 
 import numpy as np
 import pytest
 
 from rocketpy import Environment, Flight
-from rocketpy.motors.point_mass_motor import PointMassMotor
-from rocketpy.rocket.point_mass_rocket import PointMassRocket
+
+# Try to import 3DOF-specific classes, skip tests if not available
+try:
+    from rocketpy.motors.point_mass_motor import PointMassMotor
+    from rocketpy.rocket.point_mass_rocket import PointMassRocket
+
+    THREEDOF_AVAILABLE = True
+except ImportError:
+    THREEDOF_AVAILABLE = False
+    PointMassMotor = None
+    PointMassRocket = None
+
+# Skip all tests in this module if 3DOF is not available
+pytestmark = pytest.mark.skipif(
+    not THREEDOF_AVAILABLE,
+    reason="3 DOF feature (PointMassMotor, PointMassRocket) not yet available. "
+    "These tests will be enabled when issue #882 is merged.",
+)
 
 
 @pytest.fixture