- Introduced three test workflows:
- `StartInFlowchartAsExplicitStartWorkflow`: Verifies the explicit `Start` activity in a flowchart as a starting point.
- `StartInFlowchartWithStartPropertyWorkflow`: Confirms precedence of `Flowchart.Start` property over the `Start` activity.
- `StartInSequenceWorkflow`: Demonstrates successful `Start` activity usage in a sequence.
- Added integration tests (`StartTests`) ensuring expected execution flows and `Start` activity behavior for each workflow.
- Added unit tests validating `Start` activity implementation and compliance with `IStartNode`.
- Ensures test coverage for `Start` activity behavior across flowchart, sequence, and property overrides.
- Introduced `EndInFlowchartWorkflow` and `EndInSequenceWorkflow` to test `End` activity behavior in flowcharts and sequences.
- Added `EndTests` integration and unit tests to verify correct termination behavior, including `ITerminalNode` implementation.
- Updated flowchart logic to handle terminal nodes, ensuring immediate flowchart completion upon encountering `End`.
