refactor(#2464): rename hive-ag3nt crate to hive-agent, collapse lib into main

nix/host-modules/hive-c0re/environment.nix

@@ -142,7 +142,7 @@ in
     }
 // lib.optionalAttrs (config.services.hyperhive.swarm.peers != { }) {
   # Peer hives serialised as a JSON array of {domain, cert_fingerprint,
-  # wireguard_address?} objects. Consumed by hive-ag3nt::identity::peers()
+  # wireguard_address?} objects. Consumed by hive-agent::identity::peers()
   # + the dashboard's peer_hives StateSnapshot field (P33RS tab). Domain
   # is the attrset key; cert_fingerprint is null for CA-trusted peers;
   # wireguard_address is omitted when not part of the mesh.

nix/host-modules/hyperhive.nix

@@ -34,7 +34,7 @@
       first boot and drives the gateway/forge/agent URLs, with no safe
       default; changing it later is destructive). Exposed to agents as
       `HYPERHIVE_HIVE_DOMAIN`; consumed by
-      `hive-ag3nt::identity::hive_domain()` for `<name>@<domain>`
+      `hive-agent::identity::hive_domain()` for `<name>@<domain>`
       qualified labels.
     '';
   };