feat(mnemonic): add property-based tests for invalid cases

Introduce property-based tests for mnemonic file validation using Hypothesis.
Covers malformed files, invalid word counts, encoding issues, and permission
errors. Refactor test parametrization to use shared constants. Improves
robustness of CLI error handling for mnemonic derivation.

Author: mkoura

cardano_node_tests/tests/common.py

@@ -192,6 +192,7 @@ def hypothesis_settings(max_examples: int = 100) -> tp.Any:
         suppress_health_check=(
             hypothesis.HealthCheck.too_slow,
             hypothesis.HealthCheck.function_scoped_fixture,
+            hypothesis.HealthCheck.filter_too_much,
         ),
     )