feat(registry): add tart

Tart is a macOS and Linux VM tool for Apple Silicon by Cirrus Labs,
commonly used in CI environments. It uses Apple's Virtualization.framework
for near-native performance.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mnm364

registry/tart.toml

@@ -0,0 +1,4 @@
+backends = ["aqua:cirruslabs/tart"]
+description = "macOS and Linux VMs on Apple Silicon to use in CI and other automations"
+os = ["macos"]
+test = { cmd = "tart --version", expected = "{{version}}" }