feat: Update Captain navigation structure (#12761)

# Pull Request Template

## Description

This PR includes an update to the Captain navigation structure.

## Route Structure

```javascript
1. captain_assistants_responses_index    → /captain/:assistantId/faqs
2. captain_assistants_documents_index    → /captain/:assistantId/documents
3. captain_assistants_scenarios_index    → /captain/:assistantId/scenarios
4. captain_assistants_playground_index   → /captain/:assistantId/playground
5. captain_assistants_inboxes_index      → /captain/:assistantId/inboxes
6. captain_tools_index                   → /captain/tools
7. captain_assistants_settings_index     → /captain/:assistantId/settings
8. captain_assistants_guardrails_index   → /captain/:assistantId/settings/guardrails
9. captain_assistants_guidelines_index   → /captain/:assistantId/settings/guidelines
10. captain_assistants_index             → /captain/:navigationPath
```

**How it works:**

1. User clicks sidebar item → Routes to `captain_assistants_index` with
`navigationPath`
2. `AssistantsIndexPage` validates route and gets last active assistant,
if not redirects to assistant create page.
3. Routes to actual page: `/captain/:assistantId/:page`
4. Page loads with correct assistant context

Fixes
https://linear.app/chatwoot/issue/CW-5832/updating-captain-navigation

## Type of change

- [x] New feature (non-breaking change which adds functionality)

## How Has This Been Tested?




## Checklist:

- [x] My code follows the style guidelines of this project
- [x] 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
- [x] My changes generate no new warnings
- [ ] 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: Pranav <pranav@chatwoot.com>
Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/javascript/dashboard/components-next/captain/assistant/AssistantPlayground.vue

@@ -1,5 +1,5 @@
 <script setup>
-import { ref } from 'vue';
+import { ref, watch } from 'vue';
 import { useI18n } from 'vue-i18n';
 import NextButton from 'dashboard/components-next/button/Button.vue';
 import MessageList from './MessageList.vue';
@@ -29,6 +29,16 @@ const resetConversation = () => {
   newMessage.value = '';
 };
 
+// Watch for assistant ID changes and reset conversation
+watch(
+  () => assistantId,
+  (newId, oldId) => {
+    if (oldId && newId !== oldId) {
+      resetConversation();
+    }
+  }
+);
+
 const sendMessage = async () => {
   if (!newMessage.value.trim() || isLoading.value) return;
 
@@ -74,7 +84,7 @@ const sendMessage = async () => {
         </h3>
         <NextButton
           ghost
-          size="small"
+          sm
           icon="i-lucide-rotate-ccw"
           @click="resetConversation"
         />
@@ -97,7 +107,7 @@ const sendMessage = async () => {
       />
       <NextButton
         ghost
-        size="small"
+        sm
         :disabled="!newMessage.trim()"
         icon="i-lucide-send"
         @click="sendMessage"