Launch Windows desktop without a console window

[trissim]

What changed

• Declare openhcs-gui as a genuine GUI entry point instead of a console script.
• Add the GUI entry-point name to the shared installer contract and validate it against package metadata.
• Make the Windows desktop shortcut launch the installed GUI-subsystem executable directly.
• Keep the stable PowerShell adapter and openhcs.exe mcp route unchanged for MCP clients.
• Extend Windows CI to verify the shortcut target, empty argument list, and PE GUI subsystem.

Why

The desktop shortcut eventually launched a console-subsystem executable, so a terminal window could remain open for the lifetime of the GUI. Additional hidden-window flags would not correct the executable classification. Packaging metadata is the authoritative boundary for whether Windows builds a console or GUI launcher.

User impact

Launching OpenHCS from its Windows desktop shortcut opens the existing startup-progress window and application without retaining a terminal window. MCP registration and updater restart behavior remain intact.

Validation

• 53 focused installer and desktop-updater tests passed.
• A wheel build placed openhcs-gui only in [gui_scripts] and retained OpenHCS/MCP commands in [console_scripts].
• TOML and GitHub Actions workflow parsing passed.
• git diff --check and Ruff passed.
• Windows CI performs the native PowerShell and PE-subsystem acceptance checks.

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