feat(snapshot-manager): migrate snapshot management to Rust

rust/snapshot_manager/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "snapshot-manager"
+version = "0.1.0"
+edition = "2024"
+description = "Create and rotate ZFS snapshots with Signal failure alerts"
+license = "MIT"
+
+[dependencies]
+anyhow.workspace = true
+chrono.workspace = true
+clap = { workspace = true, features = ["derive", "env"] }
+env_logger.workspace = true
+log.workspace = true
+serde = { workspace = true, features = ["derive"] }
+signal.workspace = true
+toml = "0.9"
+zfs.workspace = true
+
+[dev-dependencies]
+tempfile = "3"
+
+[lints]
+workspace = true