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/Sidebar.vue

@@ -171,20 +171,24 @@ const menuItems = computed(() => {
       name: 'Captain',
       icon: 'i-woot-captain',
       label: t('SIDEBAR.CAPTAIN'),
+      showOnlyOnCloud: true,
       children: [
         {
           name: 'Assistants',
           label: t('SIDEBAR.CAPTAIN_ASSISTANTS'),
+          showOnlyOnCloud: true,
           to: accountScopedRoute('captain_assistants_index'),
         },
         {
           name: 'Documents',
           label: t('SIDEBAR.CAPTAIN_DOCUMENTS'),
+          showOnlyOnCloud: true,
           to: accountScopedRoute('captain_documents_index'),
         },
         {
           name: 'Responses',
           label: t('SIDEBAR.CAPTAIN_RESPONSES'),
+          showOnlyOnCloud: true,
           to: accountScopedRoute('captain_responses_index'),
         },
       ],
@@ -455,6 +459,7 @@ const menuItems = computed(() => {
           name: 'Settings Billing',
           label: t('SIDEBAR.BILLING'),
           icon: 'i-lucide-credit-card',
+          showOnlyOnCloud: true,
           to: accountScopedRoute('billing_settings_index'),
         },
       ],