chore: scaffold cargo workspace and crate skeletons

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/spaceshd/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "spaceshd"
+edition.workspace = true
+version.workspace = true
+
+[[bin]]
+name = "spaceshd"
+path = "src/main.rs"
+
+[dependencies]
+spacesh-proto = { path = "../spacesh-proto" }
+spacesh-pty = { path = "../spacesh-pty" }
+spacesh-core = { path = "../spacesh-core" }
+tokio.workspace = true
+tokio-util.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+bytes.workspace = true
+base64.workspace = true
+anyhow.workspace = true
+thiserror.workspace = true
+futures.workspace = true
+fs2.workspace = true
+dirs.workspace = true