feat(aren): disable orchestration, align phone prefix in config & add wix-black icon

• Orchestration disabled: wizard step 8 is hidden from the progress bar and its render case is commented out; the ORCHESTRATION backend step now redirects to summary; the orchestration tab is removed from the AREN dashboard; the agents feature card is filtered out of step-features
• Phone field UX alignment: configuration-section.tsx phone input now mirrors the wizard — country-based prefix (+33 / +212) displayed as a start adornment, only the national number is editable, and the full number (prefix + national) is sent on save
• Asset: added public/icons/wix-black.svg (black fill variant of wix-white.svg)