## Why

The current mobile experience for complex pages (Tool Workshop, Config Profiles, Repo Workspace) is broken or unusable. Tool Workshop and Config Profiles use desktop split-pane layouts that don't work on small screens, and Config Profiles isn't even accessible from mobile navigation. The Repo Workspace shows a file tree and editor side-by-side, making both unusable on phones. We need mobile-first designs for these critical configuration and workspace pages.

## What Changes

- **Mobile Navigation**: Group "Tool Workshop" and "Config Profiles" under a single "Tools" bottom nav item that opens a bottom sheet with sub-options
- **Mobile Tool Workshop**: Replace split-pane with list→detail navigation pattern (iOS Settings style)
- **Mobile Config Profiles**: Replace split-pane with list→detail navigation pattern with read-first detail view
- **Mobile Repo Workspace**: File tree as primary view with bottom tabs for Editor, Git, and Terminal
- **Desktop**: No changes to existing layouts or navigation

## Capabilities

### New Capabilities
- `mobile-tools-navigation`: Bottom sheet navigation grouping Tool Workshop and Config Profiles
- `mobile-list-detail`: List→detail navigation pattern for complex configuration pages
- `mobile-repo-workspace`: File-tree-primary workspace layout with tabbed secondary views

### Modified Capabilities
- `mobile-navigation`: Add "Tools" group with bottom sheet sub-navigation

## Impact

- Frontend: New mobile-specific components and page layouts
- Navigation: Mobile bottom nav structure changes
- No API changes required
- No database changes required
