UI not display workflow DAG as defined in python code

[yangfan0328]

Is your feature request related to a problem? Please describe.

• Uniflow pipeline tasks are stored flatly in the pipeline run spec — there is no explicit DAG/dependency graph encoded in the CRD.
• Task order/parallelism is determined dynamically from Starlark code at runtime, not statically defined in pipeline run CR
• Because the UI has no dependency graph to parse, it cannot render the correct parallel structure.

Describe the solution you'd like

• Use timeline/gantt style chart(https://developers.google.com/chart/interactive/docs/gallery/timeline) to do best presentation/view of the Uniflow workflow execution

Describe alternatives you've considered

• Define a way to express the dependency graph for Uniflow tasks — Similar to how AWS Step Functions uses Amazon States Language (ASL) to statically define workflow structure in JSON. Or adopt ASL itself for Uniflow workflow definitions.