🧪 Add missing test function calls and fix name mismatches in 09_autograd module

- Added test_unit_variable_class() call after function definition
- Added test_unit_add_operation() call after function definition
- Added test_unit_multiply_operation() call after function definition
- Added test_unit_subtract_operation() call after function definition
- Added test_unit_chain_rule() call after function definition
- Added test_module_neural_network_training() call after function definition
- Fixed function name mismatches in existing if __name__ == '__main__' calls

Ensures all test functions are executed when cells run, providing immediate feedback to students.

modules/source/09_autograd/autograd_dev.py

@@ -350,9 +350,12 @@ def test_unit_variable_class():
     print(f"✅ Data access and properties working")
     print(f"✅ Gradient management working")
 
+# Run the test
+test_unit_variable_class()
+
 # Run inline tests when module is executed directly
 if __name__ == "__main__":
-    test_variable_class()
+    test_unit_variable_class()
 
 # %% [markdown]
 """
@@ -493,6 +496,9 @@ def test_unit_add_operation():
     print(f"✅ Backward pass computing correct gradients")
     print(f"✅ Scalar addition working correctly")
 
+# Run the test
+test_unit_add_operation()
+
 # Run inline tests when module is executed directly
 if __name__ == "__main__":
     test_add_operation()
@@ -627,9 +633,12 @@ def test_unit_multiply_operation():
     print(f"✅ Backward pass implementing product rule correctly")
     print(f"✅ Scalar multiplication working correctly")
 
+# Run the test
+test_unit_multiply_operation()
+
 # Run inline tests when module is executed directly
 if __name__ == "__main__":
-    test_multiply_operation()
+    test_unit_multiply_operation()
 
 # %% nbgrader={"grade": false, "grade_id": "subtract-operation", "locked": false, "schema_version": 3, "solution": true, "task": false}
 #| export
@@ -725,9 +734,12 @@ def test_unit_subtract_operation():
     print(f"✅ Backward pass implementing subtraction rule correctly")
     print(f"✅ Scalar subtraction working correctly")
 
+# Run the test
+test_unit_subtract_operation()
+
 # Run inline tests when module is executed directly
 if __name__ == "__main__":
-    test_subtract_operation()
+    test_unit_subtract_operation()
 
 # %% [markdown]
 """
@@ -810,9 +822,12 @@ def test_unit_chain_rule():
     print(f"✅ Automatic gradient computation working correctly")
     print(f"✅ Chain rule implemented correctly")
 
+# Run the test
+test_unit_chain_rule()
+
 # Run inline tests when module is executed directly
 if __name__ == "__main__":
-    test_chain_rule()
+    test_unit_chain_rule()
 
 # %% [markdown]
 """
@@ -926,6 +941,9 @@ def test_module_neural_network_training():
     print(f"✅ Autograd enables automatic training")
     print(f"✅ Ready for complex neural network architectures!")
 
+# Run the test
+test_module_neural_network_training()
+
 # %% [markdown]
 """
 ## 🧪 Module Testing