chore(swarm-controller): drop reqwest, dead since the queue connect moved

Its only user was queue.rs, which is now swarm-queue-client. An unused
Cargo.toml dependency is not a build error, which is exactly why it
survives: the next reader takes it as still needed and copies it
forward.

swarm-controller/Cargo.toml

@@ -18,7 +18,6 @@ anyhow.workspace = true
 async-nats = { workspace = true, features = ["kv"] }
 axum.workspace = true
 futures-util.workspace = true
-reqwest.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 # The queue connect (token mint + auth callback + reconnect) is shared with