fix(fusion_helpdesk_central): findings + summary textareas span full width

The Findings and Summary fields rendered at half-width because their
enclosing <group> defaulted to col="2" — Odoo reserves a label column
even when the field has nolabel="1", so the textarea was squeezed
into the right half of the dialog while the left half sat empty.

Switch both groups to col="1" so the field uses the entire group
width. Also tag both fields with widget="text" explicitly (it was
inferred from the Text field type, but being explicit makes the
intent obvious to anyone reading the view) and migrate the button
row to a flex div so the helper text aligns with the button vertical
center.

Bumps fusion_helpdesk_central to 19.0.2.3.1.

fusion_helpdesk_central/__manifest__.py

@@ -3,7 +3,7 @@
 # License OPL-1
 {
     'name': 'Fusion Helpdesk Central — Client API Keys',
-    'version': '19.0.2.3.0',
+    'version': '19.0.2.3.1',
     'category': 'Productivity',
     'summary': 'Admin UI on the central Odoo for issuing per-client API '
                'keys used by fusion_helpdesk client deployments.',