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>

odoo-bringout-oca-payment-payment_partner/account_payment_partner/readme/CONTRIBUTORS.rst

@@ -0,0 +1,16 @@
+* Alexis de Lattre <alexis.delattre@akretion.com>
+* Raphaël Valyi
+* Stefan Rijnhart (Therp)
+* Alexandre Fayolle
+* Stéphane Bidoul <stephane.bidoul@acsone.eu>
+* Danimar Ribeiro
+* Angel Moya <angel.moya@domatix.com>
+* `Tecnativa <https://www.tecnativa.com>`_:
+
+  * Pedro M. Baeza
+  * Carlos Dauden
+  * Víctor Martínez
+* `DynApps <https://www.dynapps.be>`_:
+
+  * Raf Ven <raf.ven@dynapps.be>
+* Marçal Isern <marsal.isern@qubiq.es>