Apply OpenCloud brand colors to CTA #3505

Description

as discussed: align brand color with ui color:

dark & light:

• button background: #e2baff
• text color: #20434f

hover-state can be some generic-derived color.

Acceptance criteria

• check if colors from above can be applied to the primary color role. Might be needed to change all non-FAB-elements to non-primary roles for this, so that the primary color role can be mis-used for these hand-picked colors.
• gradient on FAB is removed (both desktop and mobile resolutions)
• petrol logo in light mode, lilac logo in dark mode