refactor: simplify Creator Dashboard to minimal Option B

Commit notes

Sales/earnings data is already in Mollie Dashboard - no need to duplicate.

Simplified dashboard now focuses on: - Mollie Connect onboarding (main CTA) - Link to Mollie Dashboard once connected - Platform-specific metrics (published packs, Pro status, fee %) - Pro upgrade upsell

Removed: - SalesChart component and Chart.js dependency - RecentSalesList, TopPacksList, StatCard components - MollieConnectCard (inlined into page) - All sales/earnings API calls and backend logic

This reduces code complexity while directing users to Mollie for comprehensive transaction and payout analytics.

Co-authored-by: armin.naimi <[email redacted]>