BUG: call evaluate_rotation_matrix in EllipticalFin/FreeFormFin __init__

EllipticalFin.__init__ and FreeFormFin.__init__ never called
self.evaluate_rotation_matrix(), unlike TrapezoidalFin. As a result the
_rotation_body_to_fin / _rotation_fin_to_body_uncanted matrices were never
created, so adding either fin to a Rocket crashed:

    Rocket.__add_single_surface -> Fin._compute_leading_edge_position
    -> AttributeError: 'EllipticalFin' object has no attribute
       '_rotation_fin_to_body_uncanted'

Both are new public classes in v1.13.0 and were fully unusable on the normal
add-to-rocket / simulate path. Existing tests only exercised the trapezoidal
singular fin, so this went uncaught.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Gui-FernandesBR

rocketpy/rocket/aero_surface/fins/elliptical_fin.py

@@ -160,6 +160,7 @@ def __init__(
         self.geometry = _EllipticalGeometry(self)
         self._update_geometry_chain()
         self.evaluate_shape()
+        self.evaluate_rotation_matrix()
 
         self.prints = _EllipticalFinPrints(self)
         self.plots = _EllipticalFinPlots(self)

rocketpy/rocket/aero_surface/fins/free_form_fin.py

@@ -148,6 +148,7 @@ def __init__(
         self.geometry = _FreeFormGeometry(self, shape_points)
         self._update_geometry_chain()
         self.evaluate_shape()
+        self.evaluate_rotation_matrix()
 
         self.prints = _FreeFormFinPrints(self)
         self.plots = _FreeFormFinPlots(self)