fix: correct step definition matching in behave tests

- Fix step definition for 'a developer has created a Container named'
- Update feature file to use consistent wording for And steps
- All step definitions now properly match feature file steps
- Behave integration verified: 22 steps matched, 0 undefined

Author: mikelane

features/basic_container.feature

@@ -46,7 +46,7 @@ Feature: Basic Container Structure
 
   Scenario: Developer creates multiple independent containers
     Given a developer has created a Container named "container_a"
-    And the developer has created a Container named "container_b"
+    And a developer has created a Container named "container_b"
     When the developer modifies "container_a"
     Then "container_b" remains unchanged
     And the containers maintain independent state

features/steps/container_steps.py

@@ -191,7 +191,7 @@ def step_response_is_iterable(context: Context) -> None:
     pass
 
 
-@given('the developer has created a Container named "{container_name}"')
+@given('a developer has created a Container named "{container_name}"')
 def step_create_named_container(context: Context, container_name: str) -> None:
     """Create a Container with a specific name for tracking."""
     from rivet_di import (