Updated project version from 1.0.1 to 1.0.2 in the `.csproj` file.
This includes changes to `<Version>`, `<AssemblyVersion>`, and
`<FileVersion>` to reflect a minor update or patch.
Refactored `CookieNames.cs` to replace the `GetEnvelopeReceiverCookieName(string key)` method with new methods for extracting envelope receiver keys from cookie names:
- Added `GetEnvelopeReceiverKeyOrDefault` to extract keys or return `null` if the format is invalid.
- Added `TryGetEnvelopeReceiverKey` to attempt key extraction with a success flag.
Updated `DigitalData.Auth.Claims.csproj` to increment `Version`, `AssemblyVersion`, and `FileVersion` from 1.0.0 to 1.0.1, reflecting the new functionality.
Added a new .NET project `DigitalData.Auth.Claims` targeting `net8.0`
with metadata for NuGet packaging. The project is configured to
not generate a NuGet package on build.
Introduced the `EnvelopeClaimNames` static class to define strongly-typed
constants for custom JWT claim names specific to envelope receiver tokens.
These include `EnvelopeId`, `EnvelopeUuid`, `ReceiverId`, and
`ReceiverSignature`. Added XML documentation for all constants.
