chore: convert to cargo workspace with four crates

Cargo.toml

@@ -1,6 +1,35 @@
-[package]
-name = "xy"
-version = "0.1.0"
-edition = "2024"
+[workspace]
+resolver = "2"
+members = [
+    "crates/xy-protocol",
+    "crates/xy-supervisor",
+    "crates/xy-ipc",
+    "crates/xy",
+]
 
-[dependencies]
+[workspace.package]
+edition = "2024"
+version = "0.1.0"
+license = "MIT OR Apache-2.0"
+
+[workspace.dependencies]
+xy-protocol = { path = "crates/xy-protocol" }
+xy-supervisor = { path = "crates/xy-supervisor" }
+xy-ipc = { path = "crates/xy-ipc" }
+
+tokio = { version = "1", features = ["rt-multi-thread", "net", "process", "signal", "sync", "fs", "io-util", "macros", "time"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+thiserror = "2"
+anyhow = "1"
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+clap = { version = "4", features = ["derive"] }
+kdl = "6"
+etcetera = "0.10"
+nix = { version = "0.30", features = ["signal", "process"] }
+humantime = "2"
+humantime-serde = "1"
+async-trait = "0.1"
+tempfile = "3"
+tokio-test = "0.4"