🧪 [testing improvement] Add tests for store update method

[johnstrand]

🎯 What: The update() method in createdStore (Squawk.ts:236) was previously untested. This PR adds a new test file Squawk.update.test.ts to cover this functionality.
📊 Coverage: The new tests cover:

• Calling update() with a single partial property
• Calling update() with multiple partial properties
• Verifying through get() that the partial state was correctly merged without overwriting the unmodified properties.
  ✨ Result: Test coverage for Squawk.ts is improved, providing more confidence in the correct functionality of the update() method, ensuring state isn't accidentally corrupted or completely replaced when update() is called with partial arguments.

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PR created automatically by Jules for task 6170546176850802217 started by @johnstrand

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