fix(fusion_helpdesk_central): wizard dialog closed on Generate Summary click

Previous fix (return True from action_generate_summary) prevented the
self-id crash but introduced a worse regression: Odoo's web client
auto-closes target='new' modals on any non-action return — the
"wizard done" convention. So Generate Summary updated the field and
then immediately killed the dialog, leaving the user with no chance
to click Send Engagement.

The only Odoo-19 idiom that reliably keeps a wizard dialog open
across a button click is to return an act_window dict that re-opens
the same wizard record (res_id=self.id). That was the original
approach — it crashed because of the active_id self-id collision in
default_get. With the active_model='helpdesk.ticket' guard now in
place (from 0104e877), the re-open is safe.

Belt-and-suspenders: the re-open action passes context={} explicitly,
so even if a future change to default_get drops the active_model
guard, there's no parent-form active_id leaking in to confuse the
ticket lookup. The wizard record is loaded by res_id directly; Odoo
19 doesn't call default_get for record loads, only for new-record
creation.

Centralised the re-open logic in _reopen_action so single + bulk
modes share the same code path.

Bumps fusion_helpdesk_central to 19.0.2.3.4.

fusion_helpdesk_central/__manifest__.py

@@ -3,7 +3,7 @@
 # License OPL-1
 {
     'name': 'Fusion Helpdesk Central — Client API Keys',
-    'version': '19.0.2.3.3',
+    'version': '19.0.2.3.4',
     'category': 'Productivity',
     'summary': 'Admin UI on the central Odoo for issuing per-client API '
                'keys used by fusion_helpdesk client deployments.',