swarm UI: log an agent into claude from its card; the credentials go to bao and the agent picks them up

A new swarm service, `swarm-claude-login`, in its own container on the host
that sets `deploy.claude-login.enable` (defaulted on by `allSwarmServices`
where the host has the minter's store leaf, like the review classifier).

- swarm-ui: an agent card showing "login needed" gets a "log in" button.
  Its dialog starts the login, shows the URL claude printed, and takes the
  pasted code.
- swarm-controller: `POST/DELETE /api/agents/{name}/claude-login` and
  `POST /api/agents/{name}/claude-login/code`, behind the swarm UI's
  authelia-gated `/api/`, relay the steps to the minter as requests on
  `$SWARM.claude-login.request`.
- swarm-claude-login: runs `claude auth login` over piped stdio with HOME
  and CLAUDE_CONFIG_DIR in a per-login scratch dir, scrapes the first
  https URL, writes the code to stdin, and stores the `.credentials.json`
  at `swarm/agents/<agent>/claude-credentials` with a KV v2 write, a new
  version over any earlier one. The scratch dir goes on every exit path; a
  login waits 15 minutes for its code.
- hive-agent: while parked in `wait_for_login`, reads that leaf every 30 s
  under the agent's own cert and installs it only when its KV version is
  newer than the one recorded in `<harness>/claude-credentials-version`.
  An equal or older version is never put back, because claude rotates the
  refresh token and the stored copy is stale after the first refresh.
- swarm-secret-client: `claude_login` paths and `SecretStore::read_versioned`.
- Credentials: a `claude-login` store leaf minted by glue-bao-tls, a
  `swarm-claude-login` policy (create/update on
  `swarm/agents/+/claude-credentials`, read on its own queue client
  secret), an authelia machine client, and a `--claude-login-client`
  grant in the queue's auth-callout responder. The unit runs as a static
  system user.

The hive's own web-UI login is unchanged.

Refs #5268

nix/module-eval/swarm-services-switch.nix

@@ -163,8 +163,9 @@ let
     lib.filter (l: swarmServiceLinkDomains ? ${l.label}) cfg.services.hyperhive.swarm.controller.links;
 
   # Every service container at once: the services-only host plus the CI
-  # runner. The CI runner, the review classifier, the builder, the metrics
-  # store and the homeserver are the five containers on a netns of their own.
+  # runner. The CI runner, the review classifier, the builder, the claude login
+  # minter, the metrics store and the homeserver are the six containers on a
+  # netns of their own.
   serviceContainersWithCi = hive {
     deploy.hive-controller.enable = false;
     deploy.allSwarmServices = true;
@@ -247,6 +248,30 @@ let
         && !(swarmServicesBaoElsewhere.containers ? swarm-builder)
         && swarmServicesBaoElsewhere.services.hyperhive.deploy.nats.enable;
     }
+    {
+      # Static, not `DynamicUser`: the user is declared in the container and
+      # the unit names it. `nats` is the control that the switch is on at all.
+      name = "hosting the swarm's shared services runs the claude login minter in its container as a static user";
+      ok =
+        let
+          c = swarmServicesHere.containers.swarm-claude-login.config;
+          sc = c.systemd.services.swarm-claude-login.serviceConfig;
+        in
+        swarmServicesHere.services.hyperhive.deploy.claude-login.enable
+        && c.users.users.swarm-claude-login.isSystemUser
+        && sc.User == "swarm-claude-login"
+        && !(sc.DynamicUser or false)
+        && swarmServicesHere.services.hyperhive.deploy.nats.enable;
+    }
+    {
+      # The minter's module asserts the store identity the store's host mints,
+      # as the classifier's does.
+      name = "the claude login minter stays off where the shared services are hosted without the store";
+      ok =
+        !swarmServicesBaoElsewhere.services.hyperhive.deploy.claude-login.enable
+        && !(swarmServicesBaoElsewhere.containers ? swarm-claude-login)
+        && swarmServicesBaoElsewhere.services.hyperhive.deploy.nats.enable;
+    }
     {
       # The switch fills in for an operator who has not spoken and yields to
       # one who has — that is what keeps a shared service placeable on a host