SEO fixes: schema cleanup, duplicate redirects, sitemap, about page

- faq.php: replace deprecated FAQPage with WebPage, remove HowTo schema
- about.php: remove incorrect Dataset schema; add Credentials and
  Founder sections (576 -> 2059 words, E-E-A-T improvement)
- .htaccess: 301 redirects for 3 duplicate article pairs
  (airflow x2, kafka x2, real-time-analytics x2)
- Canonical tags updated on redirected source articles
- sitemap-blog.xml: add 4 missing articles, remove redirect slug (47->50)

blog/articles/airflow-alternatives-python.php

@@ -18,7 +18,7 @@ header('Content-Security-Policy: default-src \'self\'; script-src \'self\' \'uns
 // SEO and performance optimizations
 $page_title = "Top 5 Airflow Alternatives for Python in 2025 | UK Guide";
 $page_description = "Looking for Python alternatives to Airflow? We review the top 5 tools like Prefect, Dagster, and Flyte for modern data pipelines. Find your best fit.";
-$canonical_url = "https://ukdataservices.co.uk/blog/articles/airflow-alternatives-python.php";
+$canonical_url = "https://ukdataservices.co.uk/blog/articles/python-airflow-alternatives";
 $keywords = "airflow alternatives python, prefect vs airflow, dagster vs airflow, python data orchestration, modern data stack, data pipeline tools uk, flyte, mage";
 $author = "UK Data Services";
 $og_image = "https://ukdataservices.co.uk/assets/images/ukds-main-logo.png";