Added `<Nullable>enable</Nullable>` to improve code safety.
Included metadata properties for NuGet packaging, such as
`<PackageId>`, `<Authors>`, `<Company>`, `<Product>`, and
more, to support package creation and distribution. Updated
the `<Description>` to detail the project's purpose and
technologies. Specified versioning details to ensure proper
version control and compatibility.
Added a new `<ItemGroup>` in `EnvelopeGenerator.ReceiverUI.csproj` to include the `Properties\PublishProfiles\` folder, enabling publishing configurations. Introduced `IISProfile.pubxml` to define publishing settings, including the use of the `Package` method, `Release` build configuration, single-file packaging, and IIS deployment path configuration.
