Improve code coverage from 79% to 94% by adding comprehensive unit tests (#348)

* Initial plan

* Initial analysis and plan for improving code coverage

Co-authored-by: samsmithnz <8389039+samsmithnz@users.noreply.github.com>

* Add comprehensive unit tests to improve code coverage to 94%

Co-authored-by: samsmithnz <8389039+samsmithnz@users.noreply.github.com>

* Potential fix for code scanning alert no. 103: Client-side URL redirect

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

* Replace Moq with NSubstitute as requested

Co-authored-by: samsmithnz <8389039+samsmithnz@users.noreply.github.com>

* Potential fix for code scanning alert no. 96: Client-side URL redirect

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

* Remove CoverageReport folder from source control

Co-authored-by: samsmithnz <8389039+samsmithnz@users.noreply.github.com>

* Fix test infrastructure: Add proper MVC services setup for controller tests

Co-authored-by: samsmithnz <8389039+samsmithnz@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: samsmithnz <8389039+samsmithnz@users.noreply.github.com>
Co-authored-by: Sam Smith <samsmithnz@gmail.com>
Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

Author: 3 people

.gitignore

@@ -328,3 +328,7 @@ ASALocalRun/
 
 # MFractors (Xamarin productivity tool) working folder 
 .mfractor/
+
+# Code coverage reports
+**/CoverageReport/
+**/TestResults/