fix: comment box mentions bug on edit

[aerodeval]

Previously when comments were edited, mentions feature didn't work correctly

Screen.Recording.2026-02-12.at.4.05.17.PM.mov

after fix:
https://github.com/user-attachments/assets/d51a936a-0b97-49b1-a8f8-f75dbd1e0e14

additionally also, the notifications sent in notify_mentions is refactored as it would send multiple notifications i.e to both users whenever the comment is edited which does not make sense.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 51.35%. Comparing base (4c73593) to head (f8311a9).
⚠️ Report is 78 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3006      +/-   ##
===========================================
+ Coverage    50.54%   51.35%   +0.80%     
===========================================
  Files          122      122              
  Lines         5403     5427      +24     
===========================================
+ Hits          2731     2787      +56     
+ Misses        2672     2640      -32     

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