De-emphasize task errors while a task is running or retrying

[marciok]

Summary

A task can retain error details while it is running a new attempt or waiting to retry. Reduce the opacity of the error section in those states so the UI communicates that the displayed error is not yet final.

Acceptance criteria

• When a task has an error and its status is running or retrying, the error section is shown with reduced opacity.
• For terminal failure states, the error section remains at normal emphasis.
• The error content remains readable and accessible.
• Add LiveView coverage for running, retrying, and failed task states.