[stevebauman]

The desktop app needs to bring the refreshed Showcode workspace into the native window and make project actions available through the operating system.

This updates the app and bundled renderer to Showcode 3.0.0.

• Adds native project menus, tab and export menus, keyboard shortcuts, file dialogs, image clipboard support, and confirmations.
• Integrates the refreshed tabs and floating controls with the macOS title bar and Windows caption controls.
• Stores acknowledged release announcements and the automatic-display preference in the desktop profile.
• Connects the toolbar update state to the existing automatic updater and fixes window restoration and IPC listener cleanup.
• Pins the shared renderer to commit 0f4beb8 from Showcode #258.

Validated with 29 desktop tests, 230 renderer tests, and a local Apple Silicon 3.0.0 build. Checked the macOS title bar, editor reordering, inspector, native export menu, and release-note dismissal/relaunch flow on macOS.