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

rust/snapshot_manager/package.nix

@@ -0,0 +1,25 @@
+{ lib, rustPlatform }:
+rustPlatform.buildRustPackage {
+  pname = "snapshot-manager";
+  version = "0.1.0";
+  src = import ../rust-source.nix { inherit lib; };
+
+  cargoLock.lockFile = ../../Cargo.lock;
+  cargoBuildFlags = [
+    "-p"
+    "snapshot-manager"
+  ];
+  cargoTestFlags = [
+    "-p"
+    "snapshot-manager"
+    "-p"
+    "signal"
+    "-p"
+    "zfs"
+  ];
+
+  meta = {
+    description = "ZFS snapshot manager with Signal failure alerts";
+    mainProgram = "snapshot-manager";
+  };
+}