Add drag-and-drop site reordering with sortOrder persistence

[mikaoelitiana]

Summary

This PR implements drag-and-drop site reordering functionality as requested in #588. Users can now reorder sites in the sidebar by dragging and dropping them.

Resolves #588

Changes

Core Implementation

1. Added sortOrder field to site data model (src/ipc-types.d.ts)

   • Optional sortOrder?: number field on StoppedSiteDetails
   • Sites without sortOrder are sorted alphabetically at the end

2. Updated sorting logic (common/lib/sort-sites.ts)

   • Modified sortSites() to prioritize sortOrder over name
   • Sites with sortOrder appear before those without

3. Added IPC handler for persistence (src/ipc-handlers.ts)

   • New updateSitesSortOrder handler to save sort order atomically
   • Uses file locking for safe concurrent access

4. Updated data persistence (src/storage/user-data.ts)

   • Added sortOrder to toDiskFormat() to persist the field to disk

5. Exposed IPC method (src/preload.ts)

   • Added updateSitesSortOrder to the renderer API

UI Implementation

6. Added drag-and-drop handlers (src/components/site-menu.tsx)

   • handleDragStart, handleDragOver, handleDrop, handleDragEnd
   • Drag handle icon from @wordpress/icons
   • Visual hover effect when dragging over items (bg-[#ffffff26])
   • Drop zone at bottom of list for dragging to end

7. Added context method (src/hooks/use-site-details.tsx)

   • New reorderSites() method in context
   • Automatically refreshes sites after reordering

Testing

8. Added comprehensive tests (common/lib/tests/sort-sites.test.ts)
   • Test sorting by sortOrder
   • Test prioritization of sortOrder over name
   • Test mixed sites with and without sortOrder

How It Works

1. Sparse Integer Strategy: Uses values like 1000, 2000, 3000... to allow inserting between items without renumbering
2. Immediate Feedback: Local state updates for instant visual feedback during drag
3. Persistence: Sort order saved to appdata-v1.json immediately on drop
4. Context Refresh: Sites re-fetched from disk after save to keep UI in sync

Backward Compatibility

• Existing sites without sortOrder continue to work
• They sort alphabetically after sites with explicit ordering
• Gradual adoption as users reorder sites

Fixes #588