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/glue-bao-tls.nix

@@ -117,6 +117,8 @@ in
       reviewClassifierClientKeyFile = lib.mkDefault "${pkiDir}/review-classifier-key.pem";
       builderClientCertFile = lib.mkDefault "${pkiDir}/builder.pem";
       builderClientKeyFile = lib.mkDefault "${pkiDir}/builder-key.pem";
+      claudeLoginClientCertFile = lib.mkDefault "${pkiDir}/claude-login.pem";
+      claudeLoginClientKeyFile = lib.mkDefault "${pkiDir}/claude-login-key.pem";
       forgePublisherClientCertFile = lib.mkDefault "${pkiDir}/forge-publisher.pem";
       forgePublisherClientKeyFile = lib.mkDefault "${pkiDir}/forge-publisher-key.pem";
       servicesIssuerClientCertFile = lib.mkDefault "${pkiDir}/services-issuer.pem";
@@ -303,6 +305,13 @@ in
         [ -s ${pkiDir}/builder.pem ] || ${signLeaf} ${pkiDir} builder \
           ${lib.escapeShellArg deployCfg.bao.builderCommonName} "" clientAuth
 
+        # The claude login minter's, which writes agents' claude credentials
+        # and reads its queue client secret. Minted here for the matrix-ctl
+        # leaf's reason: the minter is a swarm service, so on a minter host
+        # without the store this is the file an operator copies.
+        [ -s ${pkiDir}/claude-login.pem ] || ${signLeaf} ${pkiDir} claude-login \
+          ${lib.escapeShellArg deployCfg.bao.claudeLoginCommonName} "" clientAuth
+
         # The forge's token publisher. Minted here for the matrix-ctl leaf's
         # reason: the forge is a swarm singleton, so on a forge host without the
         # store this is the file an operator copies.