feat(fusion_accounting_assets): main fusion.asset model with state machine

- fusion.asset: lifecycle (draft -> running -> paused -> disposed)
- mail.thread + mail.activity.mixin tracking
- 3 depreciation methods + 3 prorate conventions selections
- monetary cost / salvage with check constraints (models.Constraint)
- computed book_value, total_depreciated, last_posted_date
- action_set_running / pause / resume / set_draft transitions
- minimal stubs for fusion.asset.category and
  fusion.asset.depreciation.line so the One2many / Many2one comodels
  resolve at registry build time; expanded in Tasks 9 + 10
- 7 new tests (47 total)

Made-with: Cursor

fusion_accounting_assets/tests/__init__.py

@@ -3,3 +3,4 @@ from . import test_prorate
 from . import test_salvage_value
 from . import test_asset_anomaly_detection
 from . import test_useful_life_predictor
+from . import test_fusion_asset

fusion_accounting_assets/tests/test_fusion_asset.py

@@ -0,0 +1,59 @@
+from datetime import date
+
+from odoo.tests.common import TransactionCase
+from odoo.tests import tagged
+from odoo.exceptions import ValidationError
+
+
+@tagged('post_install', '-at_install')
+class TestFusionAsset(TransactionCase):
+
+    def setUp(self):
+        super().setUp()
+        self.asset_vals = {
+            'name': 'Test Asset',
+            'cost': 10000,
+            'salvage_value': 1000,
+            'acquisition_date': date(2026, 1, 1),
+            'method': 'straight_line',
+            'useful_life_years': 5,
+        }
+
+    def test_create_minimal(self):
+        a = self.env['fusion.asset'].create(self.asset_vals)
+        self.assertEqual(a.state, 'draft')
+        self.assertEqual(a.book_value, 10000)
+
+    def test_state_transitions_draft_to_running(self):
+        a = self.env['fusion.asset'].create(self.asset_vals)
+        a.action_set_running()
+        self.assertEqual(a.state, 'running')
+        self.assertTrue(a.in_service_date)
+
+    def test_pause_resume(self):
+        a = self.env['fusion.asset'].create(self.asset_vals)
+        a.action_set_running()
+        a.action_pause()
+        self.assertEqual(a.state, 'paused')
+        a.action_resume()
+        self.assertEqual(a.state, 'running')
+
+    def test_cannot_pause_from_draft(self):
+        a = self.env['fusion.asset'].create(self.asset_vals)
+        with self.assertRaises(ValidationError):
+            a.action_pause()
+
+    def test_negative_cost_rejected(self):
+        with self.assertRaises(Exception):
+            self.env['fusion.asset'].create({**self.asset_vals, 'cost': -100})
+
+    def test_salvage_exceeds_cost_rejected(self):
+        with self.assertRaises(Exception):
+            self.env['fusion.asset'].create(
+                {**self.asset_vals, 'cost': 1000, 'salvage_value': 5000},
+            )
+
+    def test_book_value_starts_at_cost(self):
+        a = self.env['fusion.asset'].create(self.asset_vals)
+        self.assertEqual(a.book_value, a.cost)
+        self.assertEqual(a.total_depreciated, 0)