Multiple attachments should stack vertically with reduced orange spacing

## Problem Description

When multiple attachments are uploaded to the chat interface, there are two UI issues affecting user experience:

1. **Poor vertical stacking**: Multiple attachments are not organizing vertically as expected
2. **Excessive orange area**: Too much orange spacing is displayed, reducing usable screen real estate

## Expected Behavior

- Multiple attachments should stack vertically in a clean, organized layout
- Orange spacing should be minimized to maximize content visibility
- Attachments should display in a compact, scannable format

## Current Behavior

- Attachments display with suboptimal vertical organization
- Excessive orange area takes up unnecessary screen space
- Layout appears cluttered when multiple files are shared

## Impact

- **UX**: Poor experience when sharing multiple files
- **Efficiency**: Inefficient use of screen space
- **Usability**: Potentially confusing layout for users

## Acceptance Criteria

- [ ] Multiple attachments stack vertically in a clean layout
- [ ] Orange spacing is reduced to appropriate levels
- [ ] Layout remains responsive across different screen sizes
- [ ] File previews remain functional and accessible

## Labels

`ui`, `bug`, `chat-interface`

Start by locating the chat interface component that renders multiple attachments and reproduce the layout with several files at different screen sizes. Done means attachments stack vertically, orange spacing is reduced, the layout remains responsive, and previews stay functional and accessible.

Written by the indexing model from the issue text.