fix(test-definitions): restore field spacing in add/edit dialog tabs

The tab panels render into the Tabs component's content container, which has
no flex gap, so the per-field spacing the dialog had as a flex-column was lost.
Wrap each tab's fields in a flex-column fx-gap-3 container to restore it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: aarthy-dk

testgen/ui/components/frontend/js/pages/test_definitions.js

@@ -1461,6 +1461,8 @@ const TestDefFormContent = ({ formValues, tableColumns, testSuite, validateResul
             { activeTab },
             Tab(
                 { label: 'Parameters' },
+                div(
+                    { class: 'flex-column fx-gap-3' },
 
                 // Schema (read-only)
                 qualifiesTableRefsWithSchema
@@ -1552,9 +1554,12 @@ const TestDefFormContent = ({ formValues, tableColumns, testSuite, validateResul
                         onChange: (value) => updateField('skip_errors', value ?? 0),
                     })
                     : null,
+                ),
             ),
             Tab(
                 { label: 'Settings' },
+                div(
+                    { class: 'flex-column fx-gap-3' },
 
                 // Description override
                 Textarea({
@@ -1641,6 +1646,7 @@ const TestDefFormContent = ({ formValues, tableColumns, testSuite, validateResul
                         }),
                     ) : null,
                 ),
+                ),
             ),
         ),
 
@@ -1941,7 +1947,7 @@ stylesheet.replace(`
 .td-form-params-section {
     border-top: 1px solid var(--border-color);
     padding-top: 12px;
-    margin-top: 4px;
+    margin-top: 16px;
 }
 
 .tg-test-picker { display: flex; flex-direction: column; gap: 12px; height: 70vh; min-height: 0; }