Track DTS activity display tags for dynamic workflow tool calls

Parent: #90

## Context

During DTS validation of the dynamic workflow incident-triage sample, every workflow activity currently appears in the DTS timeline as `agents_workflow_run_tool`, even though each activity invokes a different workflow tool internally, such as `fetch_logs`, `fetch_metrics`, `fetch_deploys`, or `summarize_findings`.

This makes the DTS operator view hard to interpret. Customers will likely expect the timeline and history to show the logical tool/task identity, not only the shared Durable activity function name.

## External dependency

The DTS team indicated they are considering support for displaying tags passed from the `CallActivityAsync` call site. Once that support is released, this runtime should pass an activity/task tag that identifies the underlying workflow tool or node.

## Work to track

- Monitor the DTS release that exposes activity tags in the dashboard/timeline.
- Update the dynamic workflow Durable orchestration activity call to pass a meaningful tag, likely based on workflow node id and/or tool name.
- Validate that the DTS dashboard shows distinct activity labels for the workflow tools instead of repeated `agents_workflow_run_tool` entries.
- Update docs/sample guidance if the operator view becomes part of the DTS demo story.

## Acceptance criteria

- DTS timeline/history distinguishes workflow tool activities by logical tool/task identity.
- Dynamic workflow behavior remains unchanged for Azure Storage and DTS backends.
- The workflow incident-triage sample shows readable activity names in the DTS dashboard once the DTS feature is available.

Start by checking the dynamic workflow Durable orchestration activity call and the workflow incident-triage sample mentioned in the issue. First confirm whether the DTS release supports tags passed from CallActivityAsync, then identify how to pass the workflow node or tool identity without changing Azure Storage behavior. Done means the DTS timeline distinguishes the tools and the sample shows readable activity names once the feature is available.

Written by the indexing model from the issue text.