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/store/modules/conversationUnreadCounts.js

@@ -2,15 +2,21 @@ import ConversationAPI from '../../api/conversations';
 import types from '../mutation-types';
 
 export const state = {
+  allCount: 0,
   inboxes: {},
   labels: {},
   teams: {},
 };
 
+const normalizeCount = count => {
+  const parsedCount = Number(count);
+  return Number.isFinite(parsedCount) && parsedCount > 0 ? parsedCount : 0;
+};
+
 const normalizeCounts = counts => {
   return Object.entries(counts || {}).reduce((result, [id, count]) => {
-    const parsedCount = Number(count);
-    if (Number.isFinite(parsedCount) && parsedCount > 0) {
+    const parsedCount = normalizeCount(count);
+    if (parsedCount > 0) {
       result[String(id)] = parsedCount;
     }
 
@@ -19,6 +25,9 @@ const normalizeCounts = counts => {
 };
 
 export const getters = {
+  getAllUnreadCount($state) {
+    return $state.allCount;
+  },
   getInboxUnreadCount: $state => inboxId => {
     return $state.inboxes[String(inboxId)] || 0;
   },
@@ -55,6 +64,7 @@ export const actions = {
 
 export const mutations = {
   [types.SET_CONVERSATION_UNREAD_COUNTS]($state, payload = {}) {
+    $state.allCount = normalizeCount(payload.all_count);
     $state.inboxes = normalizeCounts(payload.inboxes);
     $state.labels = normalizeCounts(payload.labels);
     $state.teams = normalizeCounts(payload.teams);