Fix import errors: restore compatibility.py and correct NFRValidator import

Co-authored-by: fermga <203334638+fermga@users.noreply.github.com>

Author: Copilot

…r/validation/compatibility.py.deprecated src/tnfr/validation/compatibility.pysrc/tnfr/validation/compatibility.py.deprecated renamed to src/tnfr/validation/compatibility.py src/tnfr/validation/compatibility.py.deprecated renamed to src/tnfr/validation/compatibility.py

@@ -10,10 +10,10 @@
     BasicStateProjector,
     HilbertSpace,
     MathematicalDynamicsEngine,
-    NFRValidator,
     make_coherence_operator,
     make_frequency_operator,
 )
+from tnfr.validation import NFRValidator
 from tnfr.node import NodeNX
 from tnfr.structural import create_nfr