fix(x-layout): x-stack elements dont take available space (#4998)

In `Resources` and `Policies` we have nested views that are being layed
out via `XLayout` and `x-stack`. That caused that the nested views only
take the space that it needed. On wide screens that meant some white
space.
~I've changed the `size` attribute on these `XLayout`s to `max` and for
that case let children grow. So far we've only used `size=max` in
summary views for `variant=separated`, which will not conflict.~

**Before**
<img width="3011" height="1332" alt="Screenshot 2026-06-09 at 12 09 50"
src="https://github.com/user-attachments/assets/26b65c0b-de7b-48c5-bf51-7ef2b67a1b83"
/>

<img width="2996" height="1335" alt="Screenshot 2026-06-09 at 12 09 56"
src="https://github.com/user-attachments/assets/fb37cc0c-ce57-4132-ba1d-359d9aaebbfb"
/>

**After**

<img width="3012" height="1334" alt="Screenshot 2026-06-09 at 12 08 23"
src="https://github.com/user-attachments/assets/aa91c3ae-9d23-4323-a7c2-8981c497b6df"
/>

<img width="2998" height="1335" alt="Screenshot 2026-06-09 at 12 08 07"
src="https://github.com/user-attachments/assets/da03b87e-a2c9-4b79-ab07-a72ab978b13c"
/>

---------

Signed-off-by: schogges <moritz.fleck@konghq.com>

Author: schogges

packages/kuma-gui/src/app/policies/views/PolicyTypeListView.vue

@@ -121,6 +121,10 @@ import { sources } from '@/app/policies/sources'
   top: calc(var(--AppHeaderHeight) + var(--x-space-70));
   align-self: flex-start;
   max-width: 500px;
+
+  & + * {
+    flex: 1;
+  }
 }
 ul {
   list-style-type: none;

packages/kuma-gui/src/app/resources/views/ResourceTypeListView.vue

@@ -178,6 +178,10 @@ import { sources } from '@/app/resources/sources'
 .resource-type-collection {
   max-width: 500px;
   align-self: flex-start;
+
+  & + * {
+    flex: 1;
+  }
 }
 
 ul {