feat: Agent assignment policy index page with CRUD actions (#12373)

# Pull Request Template

## Description

This PR incudes new Agent assignment policy index page with CRUD
actions.

Fixes
https://linear.app/chatwoot/issue/CW-5570/feat-assignment-policy-index-page-with-actions

## Type of change

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

## How Has This Been Tested?

### Loom

https://www.loom.com/share/17ab5ceca4854f179628a3b53f347e5a?sid=cb64e881-57fd-4ae1-921b-7648653cca33

### Screenshots

**Light mode**
<img width="1428" height="888" alt="image"
src="https://github.com/user-attachments/assets/fdbb83e9-1f4f-4432-9e8a-4a8f1b810d31"
/>


**Dark mode**
<img width="1428" height="888" alt="image"
src="https://github.com/user-attachments/assets/f1fb38b9-1150-482c-ba62-3fe63ee1c7d4"
/>
<img width="726" height="495" alt="image"
src="https://github.com/user-attachments/assets/90a6ad55-9ab6-4adb-93a7-2327f5f09c79"
/>


## 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
- [ ] 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/helper/specs/commons.spec.js

@@ -5,6 +5,7 @@ import {
   convertToCategorySlug,
   convertToPortalSlug,
   sanitizeVariableSearchKey,
+  formatToTitleCase,
 } from '../commons';
 
 describe('#getTypingUsersText', () => {
@@ -142,3 +143,51 @@ describe('sanitizeVariableSearchKey', () => {
     expect(sanitizeVariableSearchKey()).toBe('');
   });
 });
+
+describe('formatToTitleCase', () => {
+  it('converts underscore-separated string to title case', () => {
+    expect(formatToTitleCase('round_robin')).toBe('Round Robin');
+  });
+
+  it('converts single word to title case', () => {
+    expect(formatToTitleCase('priority')).toBe('Priority');
+  });
+
+  it('converts multiple underscores to title case', () => {
+    expect(formatToTitleCase('auto_assignment_policy')).toBe(
+      'Auto Assignment Policy'
+    );
+  });
+
+  it('handles already capitalized words', () => {
+    expect(formatToTitleCase('HIGH_PRIORITY')).toBe('HIGH PRIORITY');
+  });
+
+  it('handles mixed case with underscores', () => {
+    expect(formatToTitleCase('first_Name_last')).toBe('First Name Last');
+  });
+
+  it('handles empty string', () => {
+    expect(formatToTitleCase('')).toBe('');
+  });
+
+  it('handles null input', () => {
+    expect(formatToTitleCase(null)).toBe('');
+  });
+
+  it('handles undefined input', () => {
+    expect(formatToTitleCase(undefined)).toBe('');
+  });
+
+  it('handles string without underscores', () => {
+    expect(formatToTitleCase('hello')).toBe('Hello');
+  });
+
+  it('handles string with numbers', () => {
+    expect(formatToTitleCase('priority_1_high')).toBe('Priority 1 High');
+  });
+
+  it('handles leading and trailing underscores', () => {
+    expect(formatToTitleCase('_leading_trailing_')).toBe('Leading Trailing');
+  });
+});