Add a component for editable task fields

[knexer]

The task detail view has some issues:

• Task detail view is ugly and not laid out at all.
• Task details with long output will expand to cover the graph view
• Task details are overwhelming, especially for LLMTasks which have multiple fields that tend to be large.
• Editing task output is a pain - itty bitty text box.
• Task output is hard to read. It should perhaps be printed better (e.g. pretty printed, multiline printed... not sure what makes sense in general. Maybe a couple modes with a toggle? Maybe a general purpose json component? Maybe allow fully custom components here??? That's surely overkill...)

This many issues in the same place calls out for a new component for the larger, editable task fields. This component would:

• Show the field name
• Elide the field data to some max size
• Be expandable
• Format the field data
• Have a delete button to clear the field
• Have an edit button to edit the field

[knexer]

Lots of work on this today! Next steps:

• add a border or other styling to make the boundaries of each task field more obvious
• fold/collapse task fields by default, showing elided un-pretty-printed json
• hide save/cancel buttons when they aren't relevant (maybe part of the above folding thing?)