[PLA-2458] Remove Platform Unity SDK References

[JayPavlina]

No description provided.

[Copilot]

Pull request overview

Removes the Unity/UPM distribution artifacts and publishing pipeline from the repository, leaving the SDK distributed via the standard .NET/NuGet path.

Changes:

• Deleted the unity-template/ UPM template assets (including Unity .meta files, link.xml, and third-party notices).
• Removed the UPM assembly script (scripts/assemble-upm.sh) and the corresponding GitHub Actions UPM publishing job.
• Updated documentation and gitignore entries to remove Unity/UPM-specific references.

Reviewed changes

Copilot reviewed 17 out of 18 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
unity-template/Third Party Notices.md.meta	Removed Unity template asset metadata.
unity-template/Third Party Notices.md	Removed Unity template third-party notice document.
unity-template/Runtime/link.xml.meta	Removed Unity template asset metadata for linker config.
unity-template/Runtime/link.xml	Removed Unity IL2CPP linker preservation rules from the Unity template.
unity-template/Runtime/Enjin.Platform.Sdk.xml.meta	Removed Unity template asset metadata for XML docs.
unity-template/Runtime/Enjin.Platform.Sdk.dll.meta	Removed Unity template asset metadata for the DLL.
unity-template/Runtime.meta	Removed Unity template folder metadata.
unity-template/README.md.meta	Removed Unity template README metadata.
unity-template/README.md	Removed Unity template documentation.
unity-template/package.json.tmpl	Removed Unity UPM manifest template.
unity-template/package.json.meta	Removed Unity template metadata for UPM manifest.
unity-template/LICENSE.md.meta	Removed Unity template metadata for license doc.
unity-template/CHANGELOG.md.meta	Removed Unity template metadata for changelog doc.
scripts/assemble-upm.sh	Removed script that assembled the Unity UPM package.
README.md	Removed Unity installation instructions and Unity compatibility note.
CHANGELOG.md	Removed mention of Unity/UPM distribution from release notes.
.gitignore	Removed ignores and exceptions related to UPM staging output and Unity .meta files.
.github/workflows/build.yml	Removed UPM publishing job and its workflow_dispatch input.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.