Allow duplicate step names in event funnels

[tudddorrr]

Remove step name uniqueness validation

• Event funnels no longer require step names to be distinct
• Removed the superRefine check that enforced unique names across funnel steps

Enable repeated action tracking

• Funnels can now track the same event name at different stages (e.g., "Started" → "Failed" → "Started")
• Useful for analyzing re-engagement patterns where users repeat actions

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.49%. Comparing base (790cab1) to head (26a3c94).
⚠️ Report is 2 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1065      +/-   ##
===========================================
- Coverage    98.49%   98.49%   -0.01%     
===========================================
  Files          488      488              
  Lines         7840     7837       -3     
  Branches      1028     1027       -1     
===========================================
- Hits          7722     7719       -3     
  Misses          49       49              
  Partials        69       69              

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