fix: remove duplicated headers from blog post bodies

- remove extracted title, byline, date, avatar, and featured image preambles
- prevent both extraction scripts from recreating duplicated headers
- add blog content duplication auditing
- update migration documentation

www/src/content/blog/en/aba-therapy-dtt-net-guide.md

@@ -12,15 +12,6 @@ category: "Library"
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-# Learn About DTT and NET Methods for More Effective ABA Therapy
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-![Rula Diab, Clinical Director, M.Ed, BCBA, LBA](/assets/images/rula-diab-avatar.jpg)
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- Rula Diab, Clinical Director, M.Ed, BCBA, LBA
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- 29 February, 2024
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-![Learn About DTT and NET Methods for More Effective ABA Therapy - hero image](/assets/images/hero-learn-dtt-net-methods.webp)
 
 In the dynamic realm of Applied Behavior Analysis (ABA) therapy, we continuously seek the most impactful strategies to cater to our learners' diverse needs. This month, I want to delve into two foundational methodologies within ABA: Discrete Trial Training (DTT) and Natural Environment Training (NET). These approaches are integral to our ABA therapeutic framework,addressing various aspects of learning, development and growth.