Sidebar tab rows should scale to 0.95 on click for a pressed feel

[amanfromsolan]

Problem

Clicking a tab row in the sidebar gives no press feedback — the row just switches selection. It should briefly scale to 0.95 while pressed so it feels physically "pressed".

Notes

• sessionRow(_:) in SidebarView.swift (~line 902) is a plain VStack with tap gestures, not a Button, so there's no isPressed state to hook into today. Either wrap the row in a Button with a pressed-scale ButtonStyle, or drive the scale from a DragGesture(minimumDistance: 0) / _onButtonGesture-style press tracker so the existing tap/double-click/drag gestures keep working.
• The file already has the pattern to copy: IconDiscButtonStyle and the picker tile style use configuration.isPressed with scaleEffect (~lines 2068, 2086).
• Press scale should anchor at the row center and spring back on release; it must not interfere with the double-click-to-rename gesture on the title or the drag-to-reorder gesture.
• Probably worth applying the same treatment to folder rows for consistency.