Add .agents/environment.yaml for automated dev environment setup

[devin-ai-integration]

Summary

Adds a .agents/environment.yaml file so future Devin sessions can automatically set up the development environment for this .NET Framework 4.5.1 / ASP.NET MVC5 project on Linux.

The config installs Mono 6.x (with MSBuild and NuGet) from the Mono Project's APT repository, restores NuGet packages, and builds the solution. It also includes knowledge entries documenting the project structure, build commands, test limitations (SQL Server LocalDB is Windows-only), and key caveats.

Verified locally: The full pipeline (apt install → nuget restore → msbuild) was run successfully, producing a 0-error build.

Review & Testing Checklist for Human

• Mono APT repo targets stable-focal (Ubuntu 20.04) — confirm this is acceptable for the VM's actual Ubuntu version (22.04 Jammy). It worked during testing but is technically a version mismatch.
• apt-key is deprecated — the GPG key import uses the legacy apt-key method, which triggers a warning. A future improvement could use /etc/apt/keyrings/ instead.
• Idempotency — running initialize multiple times will append duplicate lines to /etc/apt/sources.list.d/mono-official-stable.list. Consider whether this matters for your setup.
• Verify .agents/environment.yaml schema — confirm the initialize, maintenance, and knowledge keys match the expected Devin environment config format.

Notes

• Tests depend on SQL Server LocalDB and cannot run on Linux/Mono. This is documented in the knowledge section.
• No existing files were modified; this is a purely additive change.
• Devin Session
• Requested by: @Joseph-Gross

[devin-ai-integration]

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