feat(#2012): ship hyperhive docs as a nix asset + opt-in ~/.claude pointer

nix/templates/manager.nix

@@ -1,7 +1,13 @@
-{ ... }:
+{ lib, ... }:
 {
   # Entry-point for the privileged root agent (ruth). Referenced from
   # `flake.nix` (`nixosConfigurations.ruth`) and the meta-flake's
   # `applied/ruth/flake.nix`.
   imports = [ ./harness-base.nix ];
+
+  # The root/manager bootstraps a fresh hive, so it gets the hyperhive
+  # reference docs surfaced by default (the `~/.claude/CLAUDE.md` pointer
+  # → `$HIVE_ASSETS_DIR/docs/setup.md`). `mkDefault` so a manager's own
+  # `agent.nix` can still turn it off. Other agents default off.
+  hyperhive.docs.enable = lib.mkDefault true;
 }