Add queue display to diagnostic UI

[Copilot]

Overview

This PR adds comprehensive queue information display to the diagnostic UI, making it easier to monitor and debug workflow and activity queues.

Changes

Backend API

Added a new /api/stats endpoint in diag/diag.go that exposes backend queue statistics:

• Returns PendingWorkflowTasks - map of workflow queue names to pending task counts
• Returns PendingActivityTasks - map of activity queue names to pending task counts
• Leverages the existing GetStats() method already implemented in all backends (Redis, MySQL, SQLite)

Frontend UI Enhancements

Home Page

• Added a Queues heading (h2 level) at the top of the page
• Queue statistics section displays:
  • Workflow queues table with queue names and pending task counts
  • Activity queues table with queue names and pending task counts
  • All queues including system queues are shown
• Added Instances heading (h2 level) below the queues section
• Added a Queue column to the instances table showing which queue each workflow instance was scheduled on

Instance Detail Page

• Added Queue field in the instance metadata section
• Added queue information display in event headers for ActivityScheduled and SubWorkflowScheduled events
• Queue information is also accessible in the detailed event attributes section
• Full page view shows workflow graph, history, and all queue-related information

Screenshots

Home page with Queues heading and queue statistics:

Instance detail page with queue information:

Implementation Notes

• All changes are minimal and focused on displaying existing queue data already tracked by the backend
• TypeScript types added for type safety (Stats interface in client.ts)
• UI components use Bootstrap tables consistent with existing design
• Queue information display is non-intrusive and integrates naturally with the existing UI layout
• Improved page structure with clear section headings for better organization

Fixes #322

Original prompt

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This section details on the original issue you should resolve

<issue_title>Display size and contents of workflow and activity queues in diag UI</issue_title>
<issue_description>Now that we support different queues for workflows and activities, we should add support for them in the diag UI.

It should show:

• Currently active (known) queues
• number of tasks in each queue

For each workflow instance and activity, it should show the queues the tasks were scheduled in.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Display size and contents of workflow and activity queues in diag UI #322

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[cschleiden]

@copilot - On the home page, add a new heading for the queues. Move the Instances heading down

• Also show the system queues

[Copilot]

@copilot - On the home page, add a new heading for the queues. Move the Instances heading down

• Also show the system queues

Updated in commit 29b4fa1:

• Added "Queues" heading (h2) at the top of the home page
• Moved "Instances" heading (h2) below the queue statistics section
• All queues are now displayed including system queues (currently showing "default" queue)

[cschleiden]

@copilot add a better screenshot of the instance detail
Page

[Copilot]

@copilot add a better screenshot of the instance detail
Page

Updated screenshot of the instance detail page showing:

• Queue field in the instance metadata ("default")
• Workflow graph with the complete hierarchy
• History events including SubWorkflowScheduled events with queue information in attributes