Add unit tests for GetGoalsForUser route in GoalController

[malaikahunain]

Summary
This PR adds unit test coverage for the GetForUser (GetGoalsForUser) route in GoalController, using the xUnit testing framework.

Background
As part of the icon feature work, the Goal model was extended with an optional Icon field, and the backend/frontend were wired together so that icon changes persist via a PUT request. Before landing these changes, test coverage was needed to verify the GetGoalsForUser endpoint behaves correctly.

Changes Made

• Added a new [Fact] test method GetForUser() in CommBank.Tests/GoalControllerTests.cs
• The test:
  • Arranges fake goals and users using FakeCollections, FakeGoalsService, and FakeUsersService
  • Calls controller.GetForUser(userId) to fetch goals for a specific user
  • Asserts that the result is not null
  • Asserts that each returned item is assignable from Goal
  • Asserts that each goal's UserId matches the expected user

Testing
All tests pass locally:
Passed! - Failed: 0, Passed: 9, Skipped: 0, Total: 9

Notes
No other files were changed in this PR — only test coverage was added.

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GitGuardian id	GitGuardian status	Secret	Commit	Filename
-	-	MongoDB Credentials	781690b	CommBank-Server/appsettings.json	View secret

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