#4198 docs: point to NoMac's agent-device plugin

Summary

Adds a short NoMac section to the Device clouds page, before the Expo Simulators section and in the same shape. As discussed for #3960, NoMac's provider is a plugin that NoMac maintains outside this repository, @nomac/agent-device. The section says what NoMac runs, shows how to install the plugin and connect, and links to the plugin's README for the rest.

Touched files: 1 (website/docs/docs/device-clouds.md). No scope expansion. No linked issue.

Validation

Tested SHA: d7f005564e852131c8e487e3df6029271abadc77.

• pnpm check:affected --run --head HEAD (base: main at 0d5e5d6ae): passed. Selected 2 checks (docs-links, docs-prose), both exit 0, exactCommit=true.
• Docs-only change: runtime tests do not apply. No device-facing behavior is touched, so no device lanes are needed.
• The section's commands, run as written with agent-device 0.21.36 from npm: plugins add installs @nomac/agent-device@0.1.0, and connect nomac verifies the key.

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