Dashboard metrics view for tagged metrics could be improved.

### Is there an existing issue for this?

- [x] I have searched the existing issues

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

I want to replace the landing page for my bluesky beans bot with a trimmed down, read-only. aspire dashboard that shows a breakdown of certain metrics.

Assuming this read-only setup, with resources removed is possible, the metrics I want to show are tagged. The default graph, and the filtering experience is sub-optimal.

### Describe the solution you'd like

As you can see from the screenshot, there is a single line for the metric I am viewing, even though there are three tags.

What I would like to see, and I feel would be more useful, are four lines, one for the total, and one for each individual metric, so you can compare one against the other easily.

Even when using the tag filtering you get a single total line, rather than individual lines (with separate colours of course) which would enable the user to compare, and also look for weird spikes or other patterns.

### Additional context

_No response_

Start by locating the Aspire dashboard metrics view and its tag-filtering entry point. Compare the current aggregate graph with the requested behavior: one total line plus one line for each tagged metric, with distinct colors and useful filtering; add or update coverage for that completed behavior if the surrounding area provides tests.

Written by the indexing model from the issue text.