chore: ruff auto-fix PLR6201 — tuple → set in membership tests (#23937)

Replace  with  for all literal-tuple
membership tests. Set lookup is O(1) vs O(n) for tuple — consistent
micro-optimization across the codebase.

608 instances fixed via `ruff --fix --unsafe-fixes`, 0 remaining.
133 files, +626/-626 (net zero).

website/scripts/extract-skills.py

@@ -309,7 +309,7 @@ MIN_CATEGORY_SIZE = 4
 
 def _consolidate_small_categories(skills: list) -> list:
     for s in skills:
-        if s["category"] in ("uncategorized", ""):
+        if s["category"] in {"uncategorized", ""}:
             s["category"] = "other"
             s["categoryLabel"] = "Other"