Allow numbers starting with dot in WidgetNumber (#11108)

[Screencast from 2024-09-17 13-20-40.webm](https://github.com/user-attachments/assets/561adebb-7d93-4939-9dde-5453d5f304be)

(cherry picked from commit 5725e24)

CHANGELOG.md

@@ -20,6 +20,7 @@
 - [Fixed files associations not properly registered on Windows][11030]
 - [Fixed "rename project" button being broken after not changing project
   name][11103]
+- [Numbers starting with dot (`.5`) are accepted in Numeric Widget][11108]
 
 [10774]: https://github.com/enso-org/enso/pull/10774
 [10814]: https://github.com/enso-org/enso/pull/10814
@@ -31,6 +32,7 @@
 [11014]: https://github.com/enso-org/enso/pull/11014
 [11030]: https://github.com/enso-org/enso/pull/11030
 [11103]: https://github.com/enso-org/enso/pull/11103
+[11108]: https://github.com/enso-org/enso/pull/11108
 
 #### Enso Standard Library
 

app/gui2/src/components/widgets/NumericInputWidget.vue

@@ -28,6 +28,8 @@ const lastValidValue = ref<string>()
 watch(editedValue, (newValue) => {
   if (newValue == '' || isNumericLiteral(newValue)) {
     lastValidValue.value = newValue
+  } else if (isNumericLiteral('0' + newValue)) {
+    lastValidValue.value = '0' + newValue
   }
 })
 const valueString = computed(() => (props.modelValue != null ? props.modelValue.toString() : ''))