Finer targets

[pragmatrix]

This PR fixes the parent navigation, so that groups are focused first when navigating up.

[Copilot]

Pull request overview

This PR refactors the focus and navigation system by flattening the target hierarchy. Instead of nested variants like Band(BandTarget) and Project(ProjectTarget), targets are now direct enum variants (Instance, View, ProjectGroup, ProjectLauncher). This simplification makes group-first parent navigation possible and improves the clarity of focus path handling.

Changes:

• Flattened DesktopTarget enum variants to remove nested types
• Replaced band_location() with instance_parent() for more precise parent targeting
• Removed from_instance_and_view() helper in favor of explicit path construction

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
desktop/src/desktop_presenter.rs	Flattens DesktopTarget enum, adds conversion traits, updates navigation and camera logic to handle new flat structure
desktop/src/desktop_interaction.rs	Removes make_foreground() method and simplifies event processing by using focus() directly
desktop/src/desktop.rs	Updates focus path construction to use explicit target vectors instead of helper methods