feat(gui-v2): duplicate column name validation

Signed-off-by: Pranav C <pranavxc@gmail.com>

packages/nc-gui-v2/composables/useColumnCreateStore.ts

@@ -45,6 +45,24 @@ const [useProvideColumnCreateStore, useColumnCreateStore] = createInjectionState
           required: true,
           message: 'Column name is required',
         },
+        // validation for unique column name
+        {
+          validator: (rule: any, value: any, callback: (errMsg?: string) => void) => {
+            if (
+              meta.value?.columns?.some(
+                (c) =>
+                  c.id !== formState.value.id && // ignore current column
+                  // compare against column_name and title
+                  ((value || '').toLowerCase() === (c.column_name || '').toLowerCase() ||
+                    (value || '').toLowerCase() === (c.title || '').toLowerCase()),
+              )
+            ) {
+              callback('Duplicate column name')
+            }
+
+            callback()
+          },
+        },
       ],
       uidt: [
         {