refactor(web): sidebar list markers and draft rows live in their own files

Move the sortable shelf headers, drag boundaries and placeholders into
sidebar/SidebarListMarkers.tsx and the unsent-draft rows into
sidebar/SidebarDraftBlock.tsx. No behavior change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
af638e8f4dJulius Marminge committed on 10/21/2026, 6:56:10 AMparent12757e8

Checks

All checks passed
3 files changedLine totals unavailable