feat(fusion_accounting_ai): add DataAdapter base + registry

Made-with: Cursor

fusion_accounting_ai/tests/test_data_adapters.py

@@ -0,0 +1,27 @@
+from odoo.tests.common import TransactionCase, tagged
+from odoo.addons.fusion_accounting_ai.services.data_adapters.base import (
+    DataAdapter, AdapterMode,
+)
+
+
+@tagged('post_install', '-at_install')
+class TestDataAdapterBase(TransactionCase):
+    """Verify the data adapter base class chooses the correct backend."""
+
+    def test_adapter_mode_pure_community(self):
+        """With no fusion native and no Enterprise, adapter selects COMMUNITY."""
+        adapter = DataAdapter(self.env)
+        mode = adapter._select_mode(
+            fusion_native_model='fusion.bank.rec.widget',
+            enterprise_module='account_accountant',
+        )
+        self.assertIn(mode, (AdapterMode.FUSION, AdapterMode.ENTERPRISE, AdapterMode.COMMUNITY))
+
+    def test_adapter_falls_back_when_fusion_model_missing(self):
+        """Adapter must not error when the fusion native model isn't loaded."""
+        adapter = DataAdapter(self.env)
+        mode = adapter._select_mode(
+            fusion_native_model='fusion.never.exists',
+            enterprise_module='also_does_not_exist',
+        )
+        self.assertEqual(mode, AdapterMode.COMMUNITY)