First rudimentary implementation of the visor logic

[pragmatrix]

A start, but needs a proper Z buffer

[Copilot]

Pull request overview

This PR implements rudimentary visor launcher functionality for the desktop system. A visor is a launcher mode where multiple instances are laid out horizontally, centered within a fixed-size panel, and positioned forward in 3D space (using a z-offset). The implementation adds a new LauncherMode enum with Band and Visor variants, updates layout logic to handle visor-specific centering and sizing, and introduces z-offset calculation for instances based on their parent launcher's mode.

Changes:

• Added LauncherMode enum with Band and Visor variants to distinguish launcher behavior
• Updated layout algorithm to center visor launcher children horizontally with fixed panel sizing
• Implemented z-offset logic to position visor instances forward in 3D space (when multiple instances exist)
• Added group() method to OrderedHierarchy for retrieving sibling nodes, supporting visor layout calculations

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
desktop/src/projects/configuration/types.rs	Added LauncherMode enum and mode field to LaunchProfile
desktop/src/projects/mod.rs	Set default profile mode to Visor in ProjectConfiguration::default()
desktop/src/projects/launcher_presenter.rs	Added mode field and getter to LauncherPresenter
desktop/src/projects/configuration/toml_reader.rs	Hardcoded mode to Visor when loading profiles from TOML
desktop/src/instance_presenter.rs	Added z_offset parameter to set_rect for 3D positioning
desktop/src/desktop_system.rs	Implemented visor-specific layout logic (centering, z-offset) and refactored layout algorithm
desktop/src/aggregates/ordered_hierarchy.rs	Added group() method to retrieve sibling nodes with tests
desktop/src/desktop.rs	Set primary launcher mode to Band in desktop_groups()
.github/copilot-instructions.md	Added conventions about multiple exit points and enum import style

[Copilot]

The mode is hardcoded to LauncherMode::Visor for all profiles loaded from TOML configuration files. This means users cannot configure the launcher mode through TOML. Consider adding a "mode" field to the TOML parser that defaults to Visor if not specified, allowing users to explicitly set the mode in their configuration files.