Restructure: move packages from packages/ subdirectory to root

Flattened directory structure by moving payment packages from redundant
packages/ subdirectory to the root level of oca-payment repository.

Changes:
- Moved odoo-bringout-oca-payment-* from packages/ to root
- Updated CLAUDE.md to reflect new flat structure
- Removed redundant packages/ directory

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

CLAUDE.md

@@ -12,7 +12,7 @@
 Each package contains a single Odoo module from OCA/bank-payment:
 
 ```
-packages/
+oca-payment/
 ├── odoo-bringout-oca-payment-payment_mode/
 │   └── account_payment_mode/          # Odoo module
 ├── odoo-bringout-oca-payment-payment_partner/