feat(fusion_accounting_followup): 2 cron jobs (daily scan + weekly risk refresh)

- fusion.followup.cron AbstractModel with two handlers
- cron_fusion_followup_daily_scan: walks every overdue partner and
  delegates to engine.send_followup_email
- cron_fusion_followup_risk_refresh: weekly refresh of
  fusion_followup_risk_score / risk_band on res.partner
- V19 ir.cron records (no numbercall field)
- 2 smoke tests added (80 total)

Made-with: Cursor

fusion_accounting_followup/__manifest__.py

@@ -1,6 +1,6 @@
 {
     'name': 'Fusion Accounting Follow-up',
-    'version': '19.0.1.0.17',
+    'version': '19.0.1.0.18',
     'category': 'Accounting/Accounting',
     'summary': 'AI-augmented customer follow-ups (dunning) for unpaid invoices.',
     'description': """
@@ -33,6 +33,7 @@ menu hides; the engine + AI tools remain available for the chat.
     ],
     'data': [
         'security/ir.model.access.csv',
+        'data/cron.xml',
     ],
     'assets': {
         'web.assets_backend': [