feat: mobile Spaces nav and list-based project/workspace views

- Combine Projects and Workspaces into a single 'Spaces' grouped mobile
  nav item that opens a bottom-sheet menu.
- Add SpacesBottomSheet component with Projects/Workspaces options.
- Extend MobileListView with optional renderItem prop for rich rows.
- Redesign mobile ProjectsPage rows to show project description and
  repository chips.
- Replace mobile WorkspacesPage list with compact WorkspaceCard grid,
  matching desktop card content.
- Add mobile-list-* CSS and mobile-workspaces-list spacing.

Quality gates: npm run typecheck, npm run lint clean,
npm test -- --run 87 passed.

apps/web/src/.pi-map.index.md

@@ -2,7 +2,7 @@
 dir: apps/web/src
 
 ## role
-Provides the core web application entry point, routing infrastructure, and shared domain type definitions for a React-based frontend.
+Frontend web application entry point and core infrastructure for a React-based collaborative development platform.
 ## parent
 index: apps/web/.pi-map.index.md
 map: apps/web/.pi-map.md