Add a Custom swatch to the appearance settings accent color grid,
backed by a hex value stored in settings (synced via iCloud like the
rest). iOS uses the native ColorPicker wheel; macOS uses a circular
swatch that opens NSColorPanel, since the SwiftUI color well looks out
of place among the circles. All accent consumers now read the resolved
color through SettingsManager.resolvedAccentColor.
The indigo preset is retired from the grid but kept in the enum, so
users who selected it keep their color until they pick another one.
Claude-Session: https://claude.ai/code/session_0154KH8RAVAvm6iVanhmoW8o
Reset isCommentsExpanded and commentsFrame on the NavigationCoordinator
directly when the portrait panel is dismissed, since PortraitDetailsPanel
owns its own @State that doesn't sync back through .onChange during dismiss.
Also track comments overlay frame via GeometryReader so the dismiss gesture
can allow swipes outside the comments area instead of blanket-blocking.