Fix: stage should show pause icon when waiting for input

[rockleez]

Introduce a derived front-end flag waitingForInput on StageInfo to distinguish a running stage that is blocked on input. The UI now:

• Displays the paused glyph (two bars) instead of the running spinner.
• Keeps the running color and progress ring

Fixes #967

Testing done

• Ran a test pipeline that included the input steps in a parallel and stage view.
• Included sleeps to ensure the progress ring, progressed and paused on the waiting for input.
• Validated that the timer and pipeline status continued to show as running.
• Validated that the Console view reflected the paused status icon
• Validated that the pipeline remained in the In Progress state

Before:
Stage appears as running even though its waiting for input

After:
Stage appears as paused

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[janfaracik]

It'd be great if we could get this done via Java instead - and then just have the status change to PAUSED.

[rockleez]

It'd be great if we could get this done via Java instead - and then just have the status change to PAUSED.

i can have a look, my initial concern was that this would impact the timing as the pipeline will no longer be considered running.