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

hive-agent/src/swarm_queue.rs

@@ -210,10 +210,26 @@ impl<S: SecretSource> AgentSecret<S> {
 /// # Errors
 /// No store address, or one without the agent name or the identity beside it.
 fn store_source(get: impl Fn(&str) -> Option<String>) -> anyhow::Result<StoreSource> {
+    let (settings, role, agent) = agent_store(get)?;
+    Ok(StoreSource {
+        settings,
+        role,
+        path: queue::agent_queue_path(&agent)?,
+    })
+}
+
+/// Where the store is, the cert-auth role this agent logs in as, and the
+/// agent's name, from `get`.
+///
+/// # Errors
+/// No store address, or one without the agent name or the identity beside it.
+pub(crate) fn agent_store(
+    get: impl Fn(&str) -> Option<String>,
+) -> anyhow::Result<(Settings, String, String)> {
     if get(ENV_ADDR).is_none_or(|v| v.is_empty()) {
         anyhow::bail!(
             "{ENV_ADDR} is unset or empty, so there is no secret store to read this agent's \
-             queue credential from"
+             secrets from"
         );
     }
     let agent = get(ENV_AGENT_NAME)
@@ -221,11 +237,8 @@ fn store_source(get: impl Fn(&str) -> Option<String>) -> anyhow::Result<StoreSou
         .with_context(|| format!("{ENV_AGENT_NAME} is unset or empty"))?;
     let settings = Settings::from_lookup(|k| get(k).filter(|v| k != ENV_CACERT || ca_is_usable(v)))
         .context("reading the swarm secret store's coordinates from the environment")?;
-    Ok(StoreSource {
-        settings,
-        role: policy::agent_object_name(&agent)?,
-        path: queue::agent_queue_path(&agent)?,
-    })
+    let role = policy::agent_object_name(&agent)?;
+    Ok((settings, role, agent))
 }
 
 /// Whether the CA bundle at `path` is a file with bytes in it. `BAO_CACERT`