fix: address review issues in theme engine migration

Author: datlechin

TablePro/Theme/HexColor.swift

@@ -7,7 +7,8 @@ extension String {
         let hex = trimmingCharacters(in: .whitespacesAndNewlines)
             .trimmingCharacters(in: CharacterSet(charactersIn: "#"))
 
-        guard hex.count == 6 || hex.count == 8 else {
+        let hexLength = (hex as NSString).length
+        guard hexLength == 6 || hexLength == 8 else {
             return .gray
         }
 
@@ -18,7 +19,7 @@ extension String {
 
         let r, g, b, a: CGFloat
 
-        if hex.count == 8 {
+        if hexLength == 8 {
             r = CGFloat((value >> 24) & 0xFF) / 255.0
             g = CGFloat((value >> 16) & 0xFF) / 255.0
             b = CGFloat((value >> 8) & 0xFF) / 255.0

TablePro/Views/Results/DataGridCellFactory.swift

@@ -361,11 +361,13 @@ final class DataGridCellFactory {
     /// Maximum characters to consider per cell for width estimation
     private static let maxMeasureChars = 50
     /// Font for measuring header
-    private static let headerFont = NSFont.systemFont(ofSize: ThemeEngine.shared.activeTheme.typography.body, weight: .semibold)
+    private var headerFont: NSFont {
+        NSFont.systemFont(ofSize: ThemeEngine.shared.activeTheme.typography.body, weight: .semibold)
+    }
 
     /// Calculate column width based on header name only (used for initial display)
     func calculateColumnWidth(for columnName: String) -> CGFloat {
-        let attributes: [NSAttributedString.Key: Any] = [.font: Self.headerFont]
+        let attributes: [NSAttributedString.Key: Any] = [.font: headerFont]
         let size = (columnName as NSString).size(withAttributes: attributes)
         let width = size.width + 48 // padding for sort indicator + margins
         return min(max(width, Self.minColumnWidth), Self.maxColumnWidth)

TablePro/Views/Results/DataGridView.swift

@@ -776,11 +776,8 @@ final class TableViewCoordinator: NSObject, NSTableViewDelegate, NSTableViewData
             object: nil,
             queue: .main
         ) { [weak self] _ in
-            guard let self else { return }
-            DispatchQueue.main.async { [weak self] in
-                guard let self, let tableView = self.tableView else { return }
-                Self.updateVisibleCellFonts(tableView: tableView)
-            }
+            guard let self, let tableView = self.tableView else { return }
+            Self.updateVisibleCellFonts(tableView: tableView)
         }
     }
 

TablePro/Views/Settings/Appearance/ThemeEditorFontsSection.swift

@@ -116,17 +116,18 @@ struct ThemeEditorFontsSection: View {
     }
 
     private func updateFont(_ mutate: (inout ThemeFonts) -> Void) {
-        var updated = editingTheme ?? theme
-        mutate(&updated.fonts)
+        let base = editingTheme ?? theme
 
-        if updated.isBuiltIn {
-            var copy = engine.duplicateTheme(updated, newName: updated.name + " (Custom)")
+        if base.isBuiltIn {
+            var copy = engine.duplicateTheme(base, newName: base.name + " (Custom)")
             mutate(&copy.fonts)
             try? engine.saveUserTheme(copy)
             engine.activateTheme(copy)
             editingTheme = copy
             onThemeDuplicated?(copy)
         } else {
+            var updated = base
+            mutate(&updated.fonts)
             try? engine.saveUserTheme(updated)
             editingTheme = updated
         }

TablePro/Views/Settings/ThemePreviewCard.swift

@@ -106,15 +106,16 @@ struct ThemePreviewCard: View {
                 .fill(theme.sidebar.background.swiftUIColor)
 
             VStack(alignment: .leading, spacing: size == .compact ? 3 : 4) {
+                let widths: [CGFloat] = size == .compact
+                    ? [10, 14, 13, 9]
+                    : [14, 18, 17, 12]
                 ForEach(0..<4, id: \.self) { i in
                     RoundedRectangle(cornerRadius: 1)
                         .fill(i == 1
                             ? theme.sidebar.selectedItem.swiftUIColor.opacity(0.6)
                             : theme.sidebar.text.swiftUIColor.opacity(0.25))
                         .frame(
-                            width: i == 1
-                                ? (size == .compact ? 14 : 18)
-                                : CGFloat.random(in: size == .compact ? 8...16 : 12...20),
+                            width: widths[i],
                             height: codeLineHeight
                         )
                 }