Add SEO data generation and testing for bilingual pages

- Implemented SEO data structures for programmatic tool and collection pages.
- Created functions to build FAQs and content sections for SEO pages.
- Added tests to ensure at least 50 bilingual SEO pages are generated, no duplicate English slugs, and matching Arabic localized paths.
- Verified that both tool and collection SEO inventories are populated adequately.

backend/tests/test_sitemap.py

@@ -0,0 +1,13 @@
+"""Tests for XML sitemap exposure."""
+
+
+def test_sitemap_endpoint(client):
+    response = client.get('/sitemap.xml')
+    assert response.status_code == 200
+    assert 'xml' in response.content_type
+
+    body = response.get_data(as_text=True)
+    assert 'https://dociva.io/tools/pdf-to-word' in body
+    assert 'https://dociva.io/pdf-to-word' in body
+    assert 'https://dociva.io/ar/pdf-to-word' in body
+    assert 'https://dociva.io/arabic-pdf-tools' in body