feat: add fusion_odoo_fixes module for default Odoo patches

- New standalone module to collect fixes for default Odoo behavior
- Fix #1: account_followup never clears followup_next_action_date
  when invoices are paid, causing collection emails to fully-paid
  clients. Hooks into _invoice_paid_hook to auto-clear stale data.
- Harden Fusion Accounting followup queries with amount_residual > 0
  filter and add balance check before sending emails

Co-authored-by: Cursor <cursoragent@cursor.com>

fusion_odoo_fixes/__manifest__.py

@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+# Copyright 2025-2026 Nexa Systems Inc.
+# License OPL-1 (Odoo Proprietary License v1.0)
+
+{
+    'name': 'Fusion Odoo Fixes',
+    'version': '19.0.1.0.0',
+    'category': 'Technical',
+    'summary': 'Patches and fixes for default Odoo behavior.',
+    'description': """
+        Fusion Odoo Fixes
+        =================
+
+        A standalone module that corrects known issues in default Odoo
+        modules. Each fix is self-contained and safe to install on any
+        Odoo 19 instance.
+
+        Current Fixes
+        -------------
+        1. **Follow-up Cleanup on Payment** -- Odoo's account_followup
+           module never clears followup_next_action_date when invoices
+           are fully paid, causing collection emails to be sent to
+           clients with zero balance. This fix hooks into the payment
+           reconciliation flow and removes paid partners from the
+           follow-up queue automatically.
+    """,
+    'author': 'Nexa Systems Inc.',
+    'website': 'https://nexasystems.ca',
+    'depends': [
+        'account',
+    ],
+    'data': [],
+    'installable': True,
+    'auto_install': False,
+    'license': 'OPL-1',
+}