Open Files & Shells: combine lists and match visual style of Builders/Needs Attention

[waleedkadous]

Bug

The Open Files & Shells section needs a visual redesign:

Requirements

1. Two-column layout: Files in one column, shells in the other — side by side, not stacked as separate sub-groups
2. Match visual language: Use the same box/card style as Builders and Needs Attention sections
3. Move below Needs Attention: Needs Attention should be at the top of the Work view, Open Files & Shells should come after it
4. Include builder terminals: Builder terminals should also appear in the shells column alongside utility shells

Current State

• Shells and files split into separate sub-groups with headers
• Plain rows with no visual containment (no boxes/cards)
• Section positioned above Needs Attention
• Builder terminals excluded (only shows utility shells)