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