feat(fusion_accounting_assets): inherit account.move.line for asset linkage

- fusion_asset_id Many2one on account.move.line (ondelete='set null':
  invoice line preserved if asset is removed)
- fusion_asset_count compute (smart-button friendly)
- action_open_fusion_asset() returns a window action to jump to the asset
- 3 new tests (66 total)

Made-with: Cursor

fusion_accounting_assets/tests/__init__.py

@@ -8,3 +8,4 @@ from . import test_fusion_asset_depreciation_line
 from . import test_fusion_asset_category
 from . import test_fusion_asset_disposal
 from . import test_fusion_asset_anomaly
+from . import test_account_move_inherit

fusion_accounting_assets/tests/test_account_move_inherit.py

@@ -0,0 +1,47 @@
+from datetime import date
+
+from odoo.tests.common import TransactionCase
+from odoo.tests import tagged
+
+
+@tagged('post_install', '-at_install')
+class TestAccountMoveLineFusionAsset(TransactionCase):
+
+    def setUp(self):
+        super().setUp()
+        self.asset = self.env['fusion.asset'].create({
+            'name': 'Asset From Invoice',
+            'cost': 8000,
+            'acquisition_date': date(2026, 1, 1),
+        })
+        self.partner = self.env['res.partner'].create({'name': 'Vendor X'})
+        product = self.env['product.product'].create({'name': 'Test Asset Item'})
+        bill = self.env['account.move'].create({
+            'move_type': 'in_invoice',
+            'partner_id': self.partner.id,
+            'invoice_date': date(2026, 1, 1),
+            'invoice_line_ids': [(0, 0, {
+                'product_id': product.id,
+                'name': 'Test asset purchase',
+                'quantity': 1,
+                'price_unit': 8000,
+            })],
+        })
+        self.invoice_line = bill.invoice_line_ids[0]
+
+    def test_line_starts_without_asset_link(self):
+        self.assertFalse(self.invoice_line.fusion_asset_id)
+        self.assertEqual(self.invoice_line.fusion_asset_count, 0)
+
+    def test_link_invoice_line_to_asset(self):
+        self.invoice_line.fusion_asset_id = self.asset
+        self.assertEqual(self.invoice_line.fusion_asset_id, self.asset)
+        self.invoice_line.invalidate_recordset(['fusion_asset_count'])
+        self.assertEqual(self.invoice_line.fusion_asset_count, 1)
+
+    def test_action_open_fusion_asset_returns_window_action(self):
+        self.invoice_line.fusion_asset_id = self.asset
+        action = self.invoice_line.action_open_fusion_asset()
+        self.assertEqual(action['res_model'], 'fusion.asset')
+        self.assertEqual(action['res_id'], self.asset.id)
+        self.assertEqual(action['view_mode'], 'form')