fix(frontend): keep custom field values across create-modal type changes

Reloading the create screen after a workspace or item type change reset
every custom field value to its default, silently discarding values the
user had already entered for fields that remain configured on the new
screen. Submitting then persisted the empty default, so values picked
before a type switch (e.g. an asset Component) were lost.

Preserve entered values for fields still configured after the reload;
only fields new to the screen get their default. Applies to the desktop
store and the mobile create dialog.

Author: stefan-ernst

frontend/src/lib/mobile/MobileCreateDialog.svelte

@@ -334,10 +334,19 @@
       const customIds = fields
         .filter((field) => field.field_type === 'custom')
         .map((field) => parseInt(field.field_identifier, 10));
+      // Preserve entered values for fields that remain configured across the
+      // workspace/type change; only fields new to the screen get defaults.
+      const previousValues = customFieldValues;
       customFieldValues = {};
       for (const field of allCustomFields) {
         if (customIds.includes(field.id)) {
-          customFieldValues[field.id] = isBooleanCustomFieldType(field.field_type) ? false : '';
+          const previous = previousValues[field.id];
+          customFieldValues[field.id] =
+            previous !== undefined && previous !== null && previous !== ''
+              ? previous
+              : isBooleanCustomFieldType(field.field_type)
+                ? false
+                : '';
         }
       }
       screenFieldsLoadedForKey = key;

frontend/src/lib/stores/workItemFormStore.svelte.js

@@ -542,10 +542,20 @@ class WorkItemFormStore {
         customFieldIds.includes(field.id)
       );
 
-      // Reset custom field values for new fields
+      // Keep values the user already entered for fields that remain configured
+      // across the workspace/type change; only fields new to the screen get
+      // their default. Resetting wholesale silently discarded picks when the
+      // item type changed after a field was filled.
+      const previousValues = this.customFieldValues;
       this.customFieldValues = {};
       filteredCustomFields.forEach((field) => {
-        this.customFieldValues[field.id] = isBooleanCustomFieldType(field.field_type) ? false : '';
+        const previous = previousValues[field.id];
+        this.customFieldValues[field.id] =
+          previous !== undefined && previous !== null && previous !== ''
+            ? previous
+            : isBooleanCustomFieldType(field.field_type)
+              ? false
+              : '';
       });
 
       this.customFields = filteredCustomFields;