Add per-account folder customization page (#855)

Introduce a dedicated settings page that lets users reorder, hide,
and pin/unpin folders per account. Folders are organized into Pinned,
Categories (Gmail only), and More sections with drag-to-reorder via
ListView. New Order column on MailItemFolder persists the custom
layout; the default sort falls back to alphabetic when no custom
order is set. A reset action wipes all customization in a single
transaction and restores system-folder stickiness.

Co-authored-by: Claude <noreply@anthropic.com>

Wino.Services/DatabaseService.cs

@@ -113,6 +113,13 @@ public class DatabaseService : IDatabaseService
                 .ConfigureAwait(false);
         }
 
+        if (!folderColumns.Any(c => c.Name == nameof(MailItemFolder.Order)))
+        {
+            await Connection
+                .ExecuteAsync($"ALTER TABLE {nameof(MailItemFolder)} ADD COLUMN \"{nameof(MailItemFolder.Order)}\" INTEGER NOT NULL DEFAULT 0")
+                .ConfigureAwait(false);
+        }
+
         var customServerColumns = await Connection.GetTableInfoAsync(nameof(CustomServerInformation)).ConfigureAwait(false);
 
         if (!customServerColumns.Any(c => c.Name == nameof(CustomServerInformation.CalDavServiceUrl)))