feat(fusion_accounting_reports): period picker wizard with common presets

Adds fusion.period.picker.wizard - a guided entry point that lets users
pick a report type and a common period preset (this/last month, quarter,
YTD, last year, or custom range). The wizard uses the existing date_periods
service helpers (month_bounds, quarter_bounds, fiscal_year_bounds) to
pre-fill date_from / date_to via @api.onchange.

action_open_report returns a client action that launches the OWL reports
viewer with default_report_type / default_date_from / default_date_to /
default_comparison in the context.

Tests: 3 new (test_period_picker.py). Net 111 -> 114.
Made-with: Cursor

fusion_accounting_reports/tests/__init__.py

@@ -20,3 +20,4 @@ from . import test_account_balance_mv
 from . import test_cron
 from . import test_pdf_export
 from . import test_xlsx_export
+from . import test_period_picker

fusion_accounting_reports/tests/test_period_picker.py

@@ -0,0 +1,36 @@
+"""Tests for period picker wizard."""
+
+from odoo.tests.common import TransactionCase, tagged
+
+
+@tagged('post_install', '-at_install')
+class TestPeriodPickerWizard(TransactionCase):
+
+    def test_this_month_preset_fills_dates(self):
+        wizard = self.env['fusion.period.picker.wizard'].create({
+            'report_type': 'pnl',
+            'period_preset': 'this_month',
+        })
+        wizard._onchange_period_preset()
+        self.assertTrue(wizard.date_from)
+        self.assertTrue(wizard.date_to)
+        self.assertEqual(wizard.date_from.day, 1)
+
+    def test_this_year_preset_uses_ytd(self):
+        wizard = self.env['fusion.period.picker.wizard'].create({
+            'report_type': 'pnl',
+            'period_preset': 'this_year',
+        })
+        wizard._onchange_period_preset()
+        self.assertEqual(wizard.date_from.month, 1)
+        self.assertEqual(wizard.date_from.day, 1)
+
+    def test_action_open_report_returns_client_action(self):
+        wizard = self.env['fusion.period.picker.wizard'].create({
+            'report_type': 'pnl',
+            'period_preset': 'this_year',
+        })
+        wizard._onchange_period_preset()
+        action = wizard.action_open_report()
+        self.assertEqual(action['type'], 'ir.actions.client')
+        self.assertEqual(action['tag'], 'fusion_reports')