Add example manifests and QuickStart that match README examples

[GreedyKomodoDragon]

README contains multiple DAG examples (event-driven, scheduled, DSL) but there are no canonical example YAML files in the repo. Add a examples/ directory containing: dag-event-driven.yaml, dag-schedule.yaml, dag-dsl-example.yaml, and a sample DagRun manifest. Include a QuickStart guide that shows how to apply CRDs and create a Dag/DagRun with kubectl apply -f examples/.... This helps users validate and reproduce README examples.