itemsync: Fix updating items after moved

[hluk]

Fixes #3424

Assisted-by: gpt-5.3-codex

[codecov]

Codecov Report

❌ Patch coverage is 87.93103% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.23%. Comparing base (78272e3) to head (3b07553).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
plugins/itemsync/filewatcher.cpp	84.44%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3458      +/-   ##
==========================================
+ Coverage   80.20%   80.23%   +0.02%     
==========================================
  Files         243      243              
  Lines       30517    30564      +47     
==========================================
+ Hits        24476    24522      +46     
- Misses       6041     6042       +1     

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