[DemoApp] Update demo app colors

[paulinea]

New tokens have been applied to the demo app designs in Figma and some colors have been changed:

• Cards background color in light mode (from black to light grey) and the associated content (from white to black)
• Token category headers background (from black to light grey) and the associated content (from white to black)
• Grid illustrations background in light mode (from black to light grey)
• In Size token illustration

All these changes must be applied to the demo app.

[pylapp]

📣 New TestFlight ALPHA upload available 🚀

Please, get the new build from TestFlight app, or contact the project maintainers (@ludovic35 or @pylapp) to get access.

• Display name: OUDS Showcase ALPHA (354)
• Version: 0.9.0
• Build number: 1736158838
• Build tag: f55473c
• Build type: ALPHA
• Build details (GitHub): 354

cc @B3nz01d (product owner)
cc @pylapp @ludovic35 (dev team)
cc @MaximeTonnerre @mccart77 @iassab @TonyAntonyHello (design team)

This is an automated message sent with love thanks to Fastlane from our CI/CD pipeline 🤘

[pylapp]

📣 New TestFlight ALPHA upload available 🚀

Please, get the new build from TestFlight app, or contact the project maintainers (@ludovic35 or @pylapp) to get access.

• Display name: OUDS Showcase ALPHA (354)
• Version: 0.9.0
• Build number: 1736261986
• Build tag: 53d9059
• Build type: ALPHA
• Build details (GitHub): 354

cc @B3nz01d (product owner)
cc @pylapp @ludovic35 (dev team)
cc @MaximeTonnerre @mccart77 @iassab @TonyAntonyHello (design team)

This is an automated message sent with love thanks to Fastlane from our CI/CD pipeline 🤘

[pylapp]

📣 New TestFlight ALPHA upload available 🚀

Please, get the new build from TestFlight app, or contact the project maintainers (@ludovic35 or @pylapp) to get access.

• Display name: OUDS Showcase ALPHA (354)
• Version: 0.9.0
• Build number: 1736333003
• Build tag: feff346
• Build type: ALPHA
• Build details (GitHub): 354

cc @B3nz01d (product owner)
cc @pylapp @ludovic35 (dev team)
cc @MaximeTonnerre @mccart77 @iassab @TonyAntonyHello (design team)

This is an automated message sent with love thanks to Fastlane from our CI/CD pipeline 🤘