feat: Add frontend changes for Captain limits (#10749)

This PR introduces several improvements to the Captain AI dashboard
section:

- New billing page, with new colors, layout and meters for Captain usage
- Updated the base paywall component to use new colors
- Updated PageLayout.vue, it's more generic and can be used for other
pages as well
   - Use flags to toggle empty state and loading state
- Add prop for `featureFlag` to show the paywall slot based on feature
enabled on account
- Update `useAccount` to add a `isCloudFeatureEnabled`
- **Removed feature flag checks from captain route definitions**, so the
captain entry will always be visible on the sidebar
- Add banner to Captain pages for the following cases
   - Responses usage is over 80%
   - Documents limit is fully exhausted


### Screenshots

<details><summary>Free plan</summary>
<p>

![CleanShot 2025-01-22 at 18 37
11@2x](https://github.com/user-attachments/assets/17d3ddba-9095-4e81-9b6f-45b5f69e6a3f)
![CleanShot 2025-01-22 at 18 37
04@2x](https://github.com/user-attachments/assets/df9bb0a6-085f-45da-97d4-74cbcc33fc7e)


</p>
</details> 

<details><summary>Paid plan</summary>
<p>

![CleanShot 2025-01-22 at 18 36
45@2x](https://github.com/user-attachments/assets/a7ccf9d4-143b-49e4-8149-83c7a7985023)

![CleanShot 2025-01-22 at 20 23
57@2x](https://github.com/user-attachments/assets/c6ce35ba-e537-486d-85c8-4cc2d4e76438)


</p>
</details>

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>
Co-authored-by: Pranav <pranav@chatwoot.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/javascript/dashboard/components-next/sidebar/SidebarGroup.vue

@@ -23,6 +23,7 @@ const {
   resolvePath,
   resolvePermissions,
   resolveFeatureFlag,
+  isOnChatwootCloud,
   isAllowed,
 } = useSidebarContext();
 
@@ -41,6 +42,7 @@ const hasChildren = computed(
 const accessibleItems = computed(() => {
   if (!hasChildren.value) return [];
   return props.children.filter(child => {
+    if (child.showOnlyOnCloud && !isOnChatwootCloud.value) return false;
     // If a item has no link, it means it's just a subgroup header
     // So we don't need to check for permissions here, because there's nothing to
     // access here anyway