refactor: rename templates to agent.nix/ruth.nix, sweep stale name refs

nix/docs/default.nix

@@ -51,14 +51,14 @@ let
   };
 
   # Agent module eval from the content-addressed nixSrc. Relative
-  # imports inside agent-base.nix (the ./harness module dir) resolve
+  # imports inside agent.nix (the ./harness module dir) resolve
   # correctly against the nixSrc directory tree. `hyperhive.packages`
   # stays unset — every option default that references it carries a
   # `defaultText`, so the doc walk never forces the packages.
   agentEval = nixosSystem {
     system = pkgs.stdenv.hostPlatform.system;
     modules = [
-      "${nixSrc}/templates/agent-base.nix"
+      "${nixSrc}/templates/agent.nix"
     ];
   };
 
@@ -155,7 +155,7 @@ let
       `hyperhive.nixosModules.default` to operator host configurations
       (`services.hyperhive.{enable,domain,c0re,forge,matrix,gateway}.*`).
     - [per-agent options](agent.md) — options declared in
-      `nix/templates/harness-base.nix`, visible from every `agent.nix`
+      `nix/templates/harness/`, visible from every `agent.nix`
       (`hyperhive.model`, `hyperhive.allowedRecipients`,
       `hyperhive.extraMcpServers`, `hyperhive.frontend.*`,
       `hyperhive.forge.*`, `hyperhive.matrix.*`, `hyperhive.gui.*`).