fix: address argus review yellows on #1158

- restore count in get_loose_ends: 'N local task(s):' instead of bare 'local task(s):'
- add cross-crate coupling comment to both mcp_loose_ends_dir() copies
- add comment in hive-bash-daemon service env explaining HYPERHIVE_HARNESS_DIR
  is already injected via systemd.globalEnvironment by the meta flake

nix/templates/harness-base.nix

@@ -1130,6 +1130,14 @@ in
         HIVE_BASH_SOCKET = "/run/hive-bash/socket";
         HIVE_CONTROL_SOCKET = "/run/hive/mcp.sock";
         RUST_LOG = "info";
+        # HYPERHIVE_HARNESS_DIR and HYPERHIVE_STATE_DIR are already
+        # injected via systemd.globalEnvironment by the meta flake
+        # (set to /agents/<name>/harness and /agents/<name>/state
+        # respectively). Listed here for explicitness — the daemon
+        # uses these to derive its task + loose-ends dir paths.
+        # Without them the daemon falls back to deriving harness/ as a
+        # sibling of state/, which produces the same value but is
+        # less robust if the two vars ever diverge.
       };
       serviceConfig = {
         ExecStart = "${pkgs.hyperhive}/bin/hive-bash-daemon";