Add Tuist workspace support

[Kyle-Ye]

Summary

• Add a root Tuist workspace containing the OpenAttributeGraph and Example projects.
• Consolidate the Tuist dependency manifest, tool configuration, and setup script at the repository root.
• Define the OpenAttributeGraph internal libraries and test bundles in the root generated project.
• Add an optional source Compute backend for OpenAttributeGraphShims and cover it in CI.
• Document the default and Compute-backed workspace workflows.

Motivation

The previous setup duplicated Tuist configuration under Example and did not model the complete OpenAttributeGraph target graph. As a result, the generated workspace omitted internal and test targets, and it did not validate the Compute-backed shims path.

Impact

The repository now has one workspace-level setup flow while retaining separate OpenAttributeGraph and Example projects. Developers can generate the default workspace with Scripts/setup.sh or select the source Compute backend with Scripts/setup.sh --compute.

Validation

• Generated both default and Compute-backed workspaces.
• Built OpenAttributeGraphShims with the source Compute backend on macOS.
• Ran the generated OpenAttributeGraph test targets on macOS.
• Parsed the updated Compute workflow successfully.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 32.17%. Comparing base (480e30e) to head (6e8da61).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #235   +/-   ##
=======================================
  Coverage   32.17%   32.17%           
=======================================
  Files          71       71           
  Lines        2601     2601           
=======================================
  Hits          837      837           
  Misses       1764     1764           

Flag	Coverage Δ
ios	32.19% <ø> (ø)
macos	10.15% <ø> (ø)
ubuntu	12.03% <ø> (ø)

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[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Cache hit rate	Tests	Skipped	Ran	Commit
OpenAttributeGraph-Package	✅	0 %	137	0	137	a82548115

Builds 🔨

Scheme	Status	Duration	Commit
OpenAttributeGraph	✅	37.6s	a82548115
OpenAttributeGraph-Package	✅	1m 28s	a82548115
OpenAttributeGraphShims	✅	53.6s	a82548115