fix: Prevent race condition in preinstalled example Snap

[FrederikBolding]

Prevent a race condition in the preinstalled example Snap by using snap_setState.

---

Note

Use snap_setState for settings updates in the preinstalled example snap and update the manifest shasum.

• Preinstalled example snap:
  • Replace settings input change flow to use snap_setState with key/value, removing prior snap_manageState get+update sequence.
• Manifest:
  • Update source.shasum in packages/examples/packages/preinstalled/snap.manifest.json.

^{Written by Cursor Bugbot for commit 807ef4c. This will update automatically on new commits. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.28%. Comparing base (e5f394c) to head (807ef4c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3725   +/-   ##
=======================================
  Coverage   98.28%   98.28%           
=======================================
  Files         418      418           
  Lines       12152    12152           
  Branches     1876     1876           
=======================================
  Hits        11943    11943           
  Misses        209      209           

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