Fix button cell showing black text on initial display

Set tintColor explicitly in cell provider so the text color
is correct from the start, not only after tintColorDidChange.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

Author: ivanvorobei

Sources/DiffableKit/Table/DataSource/DiffableTableDataSource+CellProvider.swift

@@ -84,6 +84,7 @@ extension DiffableTableDataSource {
                 applyImageLayout(&content)
                 let descriptor = UIFontDescriptor.preferredFontDescriptor(withTextStyle: .body)
                 content.textProperties.font = UIFont.systemFont(ofSize: descriptor.pointSize, weight: .medium)
+                content.textProperties.color = cell.tintColor
                 cell.contentConfiguration = content
                 cell.accessoryType = item.accessoryType
                 return cell