Fix 18 dead tutorial links (TDS→Medium archive, moved/archived blogs)

[1t1sCooL]

Fixes 18 dead tutorial links (each re-verified with curl / a real browser where Cloudflare blocks curl):

• 13 Towards Data Science articles — TDS left Medium in 2025 and the old towardsdatascience.com/... URLs are dead; the same articles (same IDs, same authors) live on in Medium's "TDS Archive" publication at medium.com/data-science/.... All 13 verified.
• Thinkster (thinkster.io domain is gone, NXDOMAIN): the Django/AngularJS tutorial now points to Thinkster's own official tutorial source repo (gothinkster/thinkster-django-angular-tutorial); the generic resources entry points to the Wayback snapshot.
• "Create a Character Voting App..." (removed from sahatyalkabov.com) and "Build an Instagram Clone..." (HackHands blog gone after the Pluralsight absorption) — replaced with Wayback snapshots of the exact tutorials.
• "NLP: Count Vectorization with scikit-learn" — deleted from Medium entirely; the author (Hunter Heidenreich) republished the material on his own site, which his old post URL forwards to.