feat: Show unread count for all conversations (#14627)

## Description

Adds the unread count for All Conversations to the left sidebar. The
unread counts API now returns an `all_count` aggregate based on the same
permission-scoped inbox counts already used for sidebar badges, and the
sidebar renders that backend-provided value on the All Conversations
item.

Fixes
[CW-7240](https://linear.app/chatwoot/issue/CW-7240/unread-count-for-all-conversations)

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality not to work as expected)
- [ ] This change requires a documentation update

## How Has This Been Tested?

- `bundle exec rspec
spec/services/conversations/unread_counts/counter_spec.rb
spec/enterprise/services/conversations/unread_counts/counter_spec.rb
spec/controllers/api/v1/accounts/conversations_controller_spec.rb`
- `pnpm test
app/javascript/dashboard/store/modules/specs/conversationUnreadCounts/actions.spec.js
app/javascript/dashboard/store/modules/specs/conversationUnreadCounts/getters.spec.js
app/javascript/dashboard/store/modules/specs/conversationUnreadCounts/mutations.spec.js`
- `pnpm exec eslint
app/javascript/dashboard/components-next/sidebar/Sidebar.vue
app/javascript/dashboard/store/modules/conversationUnreadCounts.js
app/javascript/dashboard/store/modules/specs/conversationUnreadCounts/actions.spec.js
app/javascript/dashboard/store/modules/specs/conversationUnreadCounts/getters.spec.js
app/javascript/dashboard/store/modules/specs/conversationUnreadCounts/mutations.spec.js`
- `bundle exec rubocop
app/services/conversations/unread_counts/counter.rb
spec/services/conversations/unread_counts/counter_spec.rb
spec/enterprise/services/conversations/unread_counts/counter_spec.rb
spec/controllers/api/v1/accounts/conversations_controller_spec.rb`

## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

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

@@ -175,6 +175,9 @@ useEventListener(document, 'touchend', onResizeEnd);
 
 const inboxes = useMapGetter('inboxes/getInboxes');
 const labels = useMapGetter('labels/getLabelsOnSidebar');
+const allUnreadCount = useMapGetter(
+  'conversationUnreadCounts/getAllUnreadCount'
+);
 const getInboxUnreadCount = useMapGetter(
   'conversationUnreadCounts/getInboxUnreadCount'
 );
@@ -297,6 +300,7 @@ const menuItems = computed(() => {
         {
           name: 'All',
           label: t('SIDEBAR.ALL_CONVERSATIONS'),
+          badgeCount: allUnreadCount.value,
           activeOn: ['inbox_conversation'],
           to: accountScopedRoute('home'),
         },