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/host-modules/deploy.nix

@@ -700,6 +700,26 @@ in
       '';
     };
 
+    claude-login.enable = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      example = true;
+      description = ''
+        Run the claude login minter in a `swarm-claude-login` container on
+        this host. It runs `claude auth login` for the agent an operator logs
+        in from its card in the swarm UI, and writes the credentials to that
+        agent's `secret/swarm/agents/<agent>/claude-credentials`, which the
+        agent's harness installs. Run it on one host: a login in progress
+        lives in the service's memory.
+
+        On by default where
+        {option}`services.hyperhive.deploy.allSwarmServices` is set and this
+        host has the minter's store identity (the pair
+        {option}`services.hyperhive.deploy.bao.claudeLoginClientCertFile`
+        and `claudeLoginClientKeyFile`, minted on the store's host).
+      '';
+    };
+
     builder.enable = lib.mkOption {
       type = lib.types.bool;
       default = false;