feat: improve UI concerns separation

[gacallea]

At the minute, shred_pane and chuck_pane are fed information to display by two Nvim jobs. Possibly improve this by better separating concerns between NUI and the underlying needs.

• use a table instead of directly setting the NuiLine from action.
• run chuck in a detached/hidden terminal buffer
  • attach chuck_pane to it and display "raw terminal output" instead of adding lines to NUI (redundant)