feat: 🔖 v2.0.0 - Remove external providers and simplify to static Pix only

- Removed all Efí provider code and dependencies
- Simplified the codebase to only support static Pix generation
- Updated documentation and README
- Removed unnecessary files
- Updated setup scripts

Author: faguzzi3-boop

.env.example

@@ -1,13 +1,3 @@
-# Efí (Gerencianet) Configuration
-EFI_CLIENT_ID=your_efi_client_id
-EFI_CLIENT_SECRET=your_efi_client_secret
-EFI_SANDBOX=true
-
 # Server Configuration
 PORT=3000
 NODE_ENV=development
-
-# Future providers (Phase 2)
-# CIELO_CLIENT_ID=your_cielo_client_id
-# CIELO_CLIENT_SECRET=your_cielo_client_secret
-# ADYEN_API_KEY=your_adyen_api_key