Fix NorthWinds naming consistency in health check descriptions

[Copilot]

This PR addresses PR feedback to standardize the naming of "NorthWinds" throughout the codebase. The repository consistently uses "NorthWinds" (with capital W and s) in namespaces, class names, and file paths, but two health check descriptions were using the inconsistent "Northwind" variant.

Changes Made

Updated the health check registration in src/EntityFrameworkService/Startup.cs:

// Before
.AddDbContextCheck<NorthWindsContext>("Northwind database Health check")
.AddDbContextCheck<NorthWindsReadOnlyContext>("Northwind database Health check - Read only account");

// After  
.AddDbContextCheck<NorthWindsContext>("NorthWinds database Health check")
.AddDbContextCheck<NorthWindsReadOnlyContext>("NorthWinds database Health check - Read only account");

Verification

• All builds complete successfully
• All 24 tests pass across all test projects
• Comprehensive search confirms no remaining "Northwind" instances in the codebase
• Naming is now consistent with the established convention used throughout the project

The codebase now maintains complete consistency with the "NorthWinds" naming convention as used in the classic Microsoft sample database implementation.

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