chore(manifest): add tokio dep to phase-0 manifest

tokio = "1.54.1" (full features) with its lockfile tree; version pin
and feature set to be revisited with phase 1 architecture (committed
now to reduce working-tree noise)

Cargo.toml

@@ -32,6 +32,7 @@ name = "alkssh"
 default = []
 
 [dependencies]
+tokio = { version = "1.54.1", features = ["full"] }
 # Deliberately empty at initialize time — the russh version pin is phase 0
 # research output (alknet main's `russh = "0.49"` is the reference, not the
 # answer). alkcall + sibling-crate deps land with the committed architecture.
@@ -39,4 +40,4 @@ default = []
 [dev-dependencies]
 
 [profile.release]
-lto = "thin"
+lto = "thin"