feat(fusion_accounting_reports): fusion.report definition model

Persistent definition of a Fusion financial report. Each report (P&L,
balance sheet, trial balance, GL) has one row in fusion.report holding
its metadata + line specs (stored as JSON for layout flexibility).

V19 conventions: models.Constraint inline, no _sql_constraints. Per-
company uniqueness on (company_id, code).

3 new tests, 27 total passing.

Made-with: Cursor

fusion_accounting_reports/tests/__init__.py

@@ -1,2 +1,3 @@
 from . import test_services_unit
 from . import test_currency_conversion
+from . import test_fusion_report

fusion_accounting_reports/tests/test_fusion_report.py

@@ -0,0 +1,44 @@
+"""Tests for fusion.report definition model."""
+
+from odoo.tests.common import TransactionCase, tagged
+
+
+@tagged('post_install', '-at_install')
+class TestFusionReport(TransactionCase):
+
+    def test_create_minimal(self):
+        report = self.env['fusion.report'].create({
+            'name': 'Test P&L',
+            'code': 'test_pnl_minimal',
+            'report_type': 'pnl',
+        })
+        self.assertEqual(report.name, 'Test P&L')
+        self.assertTrue(report.active)
+        self.assertEqual(report.default_comparison_mode, 'none')
+
+    def test_line_specs_json_roundtrip(self):
+        specs = [
+            {'label': 'Revenue', 'account_type_prefix': 'income_', 'sign': 1},
+            {'label': 'COGS', 'account_type_prefix': 'expense_direct_', 'sign': -1},
+        ]
+        report = self.env['fusion.report'].create({
+            'name': 'Test',
+            'code': 'test_json_roundtrip',
+            'report_type': 'pnl',
+            'line_specs': specs,
+        })
+        self.assertEqual(report.line_specs, specs)
+        self.assertEqual(report.line_specs[0]['label'], 'Revenue')
+
+    def test_company_code_uniqueness(self):
+        self.env['fusion.report'].create({
+            'name': 'A',
+            'code': 'dup_code_test',
+            'report_type': 'pnl',
+        })
+        with self.assertRaises(Exception):
+            self.env['fusion.report'].create({
+                'name': 'B',
+                'code': 'dup_code_test',
+                'report_type': 'pnl',
+            })