feat: preview host protocol and hide guard

Cargo.toml

@@ -15,6 +15,7 @@ niri-ipc = "=26.4.0"
 rustix = { version = "1.1.5", features = ["event", "fs", "pipe", "process", "stdio"] }
 serde = { version = "1.0.229", features = ["derive"] }
 serde_ignored = "0.1.14"
+serde_json = "1.0.151"
 smithay-client-toolkit = "0.21.1"
 toml = "1.1.6"
 tracing = "0.1.44"