Add Linker and Optimizer modules with API integration and frontend components

- Added Linker and Optimizer apps to `INSTALLED_APPS` in `settings.py`.
- Configured API endpoints for Linker and Optimizer in `urls.py`.
- Implemented `OptimizeContentFunction` for content optimization in the AI module.
- Created prompts for content optimization and site structure generation.
- Updated `OptimizerService` to utilize the new AI function for content optimization.
- Developed frontend components including dashboards and content lists for Linker and Optimizer.
- Integrated new routes and sidebar navigation for Linker and Optimizer in the frontend.
- Enhanced content management with source and sync status filters in the Writer module.
- Comprehensive test coverage added for new features and components.

backend/igny8_core/modules/linker/tests/__init__.py

@@ -0,0 +1,2 @@
+# Linker module tests
+

backend/igny8_core/modules/linker/tests/test_views.py

@@ -0,0 +1,137 @@
+"""
+Tests for Linker API endpoints
+"""
+from unittest.mock import patch
+from django.test import TestCase
+from rest_framework.test import APIClient
+from rest_framework import status
+from igny8_core.business.content.models import Content
+from igny8_core.business.billing.exceptions import InsufficientCreditsError
+from igny8_core.api.tests.test_integration_base import IntegrationTestBase
+
+
+class LinkerAPITests(IntegrationTestBase):
+    """Tests for Linker API endpoints"""
+    
+    def setUp(self):
+        super().setUp()
+        self.client = APIClient()
+        self.client.force_authenticate(user=self.user)
+        
+        # Create test content
+        self.content = Content.objects.create(
+            account=self.account,
+            site=self.site,
+            sector=self.sector,
+            title="Test Content",
+            html_content="<p>Test content.</p>",
+            word_count=100,
+            status='draft'
+        )
+    
+    def test_process_endpoint_requires_authentication(self):
+        """Test that process endpoint requires authentication"""
+        client = APIClient()  # Not authenticated
+        response = client.post('/api/v1/linker/process/', {
+            'content_id': self.content.id
+        })
+        
+        self.assertEqual(response.status_code, status.HTTP_401_UNAUTHORIZED)
+    
+    @patch('igny8_core.modules.linker.views.LinkerService.process')
+    def test_process_endpoint_success(self, mock_process):
+        """Test successful processing"""
+        mock_content = Content.objects.create(
+            account=self.account,
+            site=self.site,
+            sector=self.sector,
+            title="Linked Content",
+            html_content="<p>Linked.</p>",
+            internal_links=[{'content_id': 1, 'anchor_text': 'test'}],
+            linker_version=1,
+            word_count=100
+        )
+        mock_process.return_value = mock_content
+        
+        response = self.client.post('/api/v1/linker/process/', {
+            'content_id': self.content.id
+        }, format='json')
+        
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertTrue(response.data['success'])
+        self.assertEqual(response.data['data']['content_id'], self.content.id)
+        self.assertEqual(response.data['data']['links_added'], 1)
+    
+    def test_process_endpoint_invalid_content_id(self):
+        """Test process endpoint with invalid content ID"""
+        response = self.client.post('/api/v1/linker/process/', {
+            'content_id': 99999
+        }, format='json')
+        
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+    
+    @patch('igny8_core.modules.linker.views.LinkerService.process')
+    def test_process_endpoint_insufficient_credits(self, mock_process):
+        """Test process endpoint with insufficient credits"""
+        mock_process.side_effect = InsufficientCreditsError("Insufficient credits")
+        
+        response = self.client.post('/api/v1/linker/process/', {
+            'content_id': self.content.id
+        }, format='json')
+        
+        self.assertEqual(response.status_code, status.HTTP_402_PAYMENT_REQUIRED)
+    
+    @patch('igny8_core.modules.linker.views.LinkerService.batch_process')
+    def test_batch_process_endpoint_success(self, mock_batch):
+        """Test successful batch processing"""
+        content2 = Content.objects.create(
+            account=self.account,
+            site=self.site,
+            sector=self.sector,
+            title="Content 2",
+            word_count=100
+        )
+        
+        mock_batch.return_value = [self.content, content2]
+        
+        response = self.client.post('/api/v1/linker/batch_process/', {
+            'content_ids': [self.content.id, content2.id]
+        }, format='json')
+        
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertTrue(response.data['success'])
+        self.assertEqual(len(response.data['data']), 2)
+    
+    def test_batch_process_endpoint_validation(self):
+        """Test batch process endpoint validation"""
+        response = self.client.post('/api/v1/linker/batch_process/', {
+            'content_ids': []  # Empty list
+        }, format='json')
+        
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+    
+    def test_process_endpoint_respects_account_isolation(self):
+        """Test that process endpoint respects account isolation"""
+        from igny8_core.auth.models import Account
+        other_account = Account.objects.create(
+            name="Other Account",
+            slug="other",
+            plan=self.plan,
+            owner=self.user
+        )
+        
+        other_content = Content.objects.create(
+            account=other_account,
+            site=self.site,
+            sector=self.sector,
+            title="Other Content",
+            word_count=100
+        )
+        
+        response = self.client.post('/api/v1/linker/process/', {
+            'content_id': other_content.id
+        }, format='json')
+        
+        # Should return 400 because content belongs to different account
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+