Add FluentValidation for Question model validation

- Updated `AskEndpoints.cs` to include `MinimalHelpers.FluentValidation` and standardize endpoint descriptions.
- Integrated FluentValidation in `Program.cs` and registered validators.
- Modified `SqlDatabaseVectorSearch.csproj` to add necessary package references for FluentValidation.
- Created `QuestionValidator` class to enforce validation rules on the `Question` model.

SqlDatabaseVectorSearch/SqlDatabaseVectorSearch.csproj

@@ -12,6 +12,7 @@
         <PackageReference Include="DocumentFormat.OpenXml" Version="3.3.0" />
         <PackageReference Include="EFCore.SqlServer.VectorSearch" Version="9.0.0-preview.2" />
         <PackageReference Include="EntityFrameworkCore.Exceptions.SqlServer" Version="8.1.3" />
+        <PackageReference Include="FluentValidation.DependencyInjectionExtensions" Version="12.0.0" />
         <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="9.0.4" />
         <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="9.0.4" />
         <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="9.0.4">
@@ -25,6 +26,7 @@
         <PackageReference Include="Microsoft.ML.Tokenizers.Data.O200kBase" Version="1.0.2" />
         <PackageReference Include="Microsoft.SemanticKernel" Version="1.48.0" />
         <PackageReference Include="MimeMapping" Version="3.1.0" />
+        <PackageReference Include="MinimalHelpers.FluentValidation" Version="1.1.3" />
         <PackageReference Include="MinimalHelpers.Routing.Analyzers" Version="1.1.3" />
         <PackageReference Include="PdfPig" Version="0.1.10" />
         <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="8.1.1" />