implemented submission guard for promotion form

ui/src/components/promotions/promotionForm.vue

@@ -31,8 +31,12 @@ const { handleSubmit, errors, values, resetForm, setFieldValue, submitCount } =
     validateOnMount: false,
 })
 
+const submitting = ref(false);
+
 const submitForm = handleSubmit(
     async (vals) => {
+        if (submitting.value) return;
+        submitting.value = true;
         try {
             let output = vals;
             output.promotions.map(p => p.start_date = new Date(p.start_date).toISOString())
@@ -42,6 +46,8 @@ const submitForm = handleSubmit(
         } catch (error) {
             submitError.value = error;
             console.error(error);
+        } finally {
+            submitting.value = false;
         }
     }
 );
@@ -281,7 +287,12 @@ function setAllToday() {
                 </VeeField>
                 <div class="flex flex-col items-end gap-2">
                     <div class="h-6" />
-                    <Button type="submit" class="w-min">Submit</Button>
+                    <Button type="submit" form="trainingForm" :disabled="submitting" class="w-35">
+                        <span class="flex items-center gap-2" v-if="submitting">
+                            <Spinner></Spinner> Submitting…
+                        </span>
+                        <span v-else>Submit</span>
+                    </Button>
                     <p v-if="submitError" class="text-destructive">{{ submitError }}</p>
                     <div v-else class="h-6 flex justify-end">
                         <p v-if="submitCount > 0 && errors.promotions && typeof errors.promotions === 'string'"