fix: V2 Assignment service enhancements (#13036)

## Linear Ticket:
https://linear.app/chatwoot/issue/CW-6081/review-feedback

## Description

Assignment V2 Service Enhancements

- Enable Assignment V2 on plan upgrade
- Fix UI issue with fair distribution policy display
- Add advanced assignment feature flag and enhance Assignment V2
capabilities

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)

## How Has This Been Tested?

This has been tested using the UI.

## Checklist:

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

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Changes auto-assignment execution paths, rate limiting defaults, and
feature-flag gating (including premium plan behavior), which could
affect which conversations get assigned and when. UI rewires inbox
settings and policy flows, so regressions are possible around
navigation/linking and feature visibility.
> 
> **Overview**
> **Adds a new premium `advanced_assignment` feature flag** and uses it
to gate capacity/balanced assignment features in the UI (sidebar entry,
settings routes, assignment-policy landing cards) and backend
(Enterprise balanced selector + capacity filtering).
`advanced_assignment` is marked premium, included in Business plan
entitlements, and auto-synced in Enterprise accounts when
`assignment_v2` is toggled.
> 
> **Improves Assignment V2 policy UX** by adding an inbox-level
“Conversation Assignment” section (behind `assignment_v2`) that can
link/unlink an assignment policy, navigate to create/edit policy flows
with `inboxId` query context, and show an inbox-link prompt after
creating a policy. The policy form now defaults to enabled, disables the
`balanced` option with a premium badge/message when unavailable, and
inbox lists support click-to-navigate.
> 
> **Tightens/adjusts auto-assignment behavior**: bulk assignment now
requires `inbox.enable_auto_assignment?`, conversation ordering uses the
attached `assignment_policy` priority, and rate limiting uses
`assignment_policy` config with an infinite default limit while still
tracking assignments. Tests and i18n strings are updated accordingly.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
23bc03bf75ee4376071e4d7fc7cd564c601d33d7. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Co-authored-by: Pranav <pranav@chatwoot.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Shivam Mishra <scm.mymail@gmail.com>

app/javascript/dashboard/components-next/AssignmentPolicy/components/RadioCard.vue

@@ -1,4 +1,6 @@
 <script setup>
+import { useI18n } from 'vue-i18n';
+
 const props = defineProps({
   id: {
     type: String,
@@ -16,12 +18,22 @@ const props = defineProps({
     type: Boolean,
     default: false,
   },
+  disabled: {
+    type: Boolean,
+    default: false,
+  },
+  disabledMessage: {
+    type: String,
+    default: '',
+  },
 });
 
 const emit = defineEmits(['select']);
 
+const { t } = useI18n();
+
 const handleChange = () => {
-  if (!props.isActive) {
+  if (!props.isActive && !props.disabled) {
     emit('select', props.id);
   }
 };
@@ -29,9 +41,11 @@ const handleChange = () => {
 
 <template>
   <div
-    class="relative cursor-pointer rounded-xl outline outline-1 p-4 transition-all duration-200 bg-n-solid-1 py-4 ltr:pl-4 rtl:pr-4 ltr:pr-6 rtl:pl-6"
+    class="relative rounded-xl outline outline-1 p-4 transition-all duration-200 bg-n-solid-1 py-4 ltr:pl-4 rtl:pr-4 ltr:pr-6 rtl:pl-6"
     :class="[
-      isActive ? 'outline-n-blue-9' : 'outline-n-weak hover:outline-n-strong',
+      disabled ? 'opacity-50 cursor-not-allowed' : 'cursor-pointer',
+      isActive ? 'outline-n-blue-9' : 'outline-n-weak',
+      !disabled && !isActive ? 'hover:outline-n-strong' : '',
     ]"
     @click="handleChange"
   >
@@ -41,6 +55,7 @@ const handleChange = () => {
         :checked="isActive"
         :value="id"
         :name="id"
+        :disabled="disabled"
         type="radio"
         class="h-4 w-4 border-n-slate-6 text-n-brand focus:ring-n-brand focus:ring-offset-0"
         @change="handleChange"
@@ -49,11 +64,23 @@ const handleChange = () => {
 
     <!-- Content -->
     <div class="flex flex-col gap-3 items-start">
-      <h3 class="text-sm font-medium text-n-slate-12">
-        {{ label }}
-      </h3>
+      <div class="flex items-center gap-2">
+        <h3 class="text-sm font-medium text-n-slate-12">
+          {{ label }}
+        </h3>
+        <span
+          v-if="disabled"
+          class="inline-flex items-center px-2 py-0.5 rounded text-xs font-medium bg-n-yellow-3 text-n-yellow-11"
+        >
+          {{
+            t(
+              'ASSIGNMENT_POLICY.AGENT_ASSIGNMENT_POLICY.FORM.ASSIGNMENT_ORDER.BALANCED.PREMIUM_BADGE'
+            )
+          }}
+        </span>
+      </div>
       <p class="text-sm text-n-slate-11">
-        {{ description }}
+        {{ disabled && disabledMessage ? disabledMessage : description }}
       </p>
     </div>
   </div>