chore: Replace campaign mixin with composable [CW-3463] (#9987)

# Pull Request Template

## Description

Repalces campaignMixin and its usage with the new useCampaign mixin

Fixes
https://linear.app/chatwoot/issue/CW-3463/rewrite-campaignmixin-mixin-to-a-composable

---------

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

app/javascript/shared/composables/specs/useCampaign.spec.js

@@ -0,0 +1,47 @@
+import { describe, it, expect, vi } from 'vitest';
+import { useCampaign } from '../useCampaign';
+import { useRoute } from 'dashboard/composables/route';
+import { CAMPAIGN_TYPES } from '../../constants/campaign';
+
+// Mock the useRoute composable
+vi.mock('dashboard/composables/route', () => ({
+  useRoute: vi.fn(),
+}));
+
+describe('useCampaign', () => {
+  it('returns the correct campaign type for ongoing campaigns', () => {
+    useRoute.mockReturnValue({ name: 'ongoing_campaigns' });
+    const { campaignType } = useCampaign();
+    expect(campaignType.value).toBe(CAMPAIGN_TYPES.ONGOING);
+  });
+
+  it('returns the correct campaign type for one-off campaigns', () => {
+    useRoute.mockReturnValue({ name: 'one_off' });
+    const { campaignType } = useCampaign();
+    expect(campaignType.value).toBe(CAMPAIGN_TYPES.ONE_OFF);
+  });
+
+  it('isOngoingType returns true for ongoing campaigns', () => {
+    useRoute.mockReturnValue({ name: 'ongoing_campaigns' });
+    const { isOngoingType } = useCampaign();
+    expect(isOngoingType.value).toBe(true);
+  });
+
+  it('isOngoingType returns false for one-off campaigns', () => {
+    useRoute.mockReturnValue({ name: 'one_off' });
+    const { isOngoingType } = useCampaign();
+    expect(isOngoingType.value).toBe(false);
+  });
+
+  it('isOneOffType returns true for one-off campaigns', () => {
+    useRoute.mockReturnValue({ name: 'one_off' });
+    const { isOneOffType } = useCampaign();
+    expect(isOneOffType.value).toBe(true);
+  });
+
+  it('isOneOffType returns false for ongoing campaigns', () => {
+    useRoute.mockReturnValue({ name: 'ongoing_campaigns' });
+    const { isOneOffType } = useCampaign();
+    expect(isOneOffType.value).toBe(false);
+  });
+});