Add drag-and-drop workspace reordering with persistent sort order (Vibe Kanban)

[stunningpixels]

Summary

• Added drag-and-drop reordering for workspaces in the sidebar
• Implemented persistent sort order that survives across sessions
• Uses fractional indexing for efficient reordering (single API call per drag operation)
• Supports reordering within both active and archived workspace views
• Pinned workspaces stay grouped at top; reordering works within pinned/unpinned groups separately

Test plan

• [ ] Create several workspaces and verify they appear newest-first by default
• [ ] Drag a workspace to reorder it within unpinned workspaces
• [ ] Pin some workspaces and verify pinned group stays at top
• [ ] Drag to reorder within pinned workspaces
• [ ] Archive workspaces and switch to archived view
• [ ] Verify archived workspaces appear newest-first
• [ ] Drag to reorder archived workspaces
• [ ] Refresh the page and verify all reordering persists

Changes

Database

• Added sort_order column (REAL type for fractional indexing) to workspaces table
• Migration initializes existing workspaces with sort order based on creation date (newest first)
• New workspaces default to sort_order=0, appearing at top of the list

Backend (Rust)

• Extended Workspace model with sort_order: f64 field
• Updated all workspace SQL queries to include sort_order
• Extended UpdateWorkspace endpoint to accept optional sort_order parameter

Frontend (TypeScript/React)

• Installed @dnd-kit/sortable package
• Created SortableWorkspaceItem component with drag handle and visual feedback
• Wrapped workspace lists in DndContext and SortableContext providers
• Implemented calculateNewSortOrder using fractional indexing algorithm
• Added optimistic updates for smooth drag-and-drop UX
• Updated sorting logic: pinned first, then by sort_order ascending

Key Implementation Details

• Fractional indexing: When moving an item, its new sort_order is calculated as the midpoint between its new neighbors, avoiding the need to update multiple records
• Optimistic updates: UI updates immediately on drag end, API call happens in background
• Separation of concerns: State management in container component, presentation in view component (per ESLint rules)

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This PR was written using Vibe Kanban

🤖 Generated with Claude Code