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/login.rs

@@ -15,6 +15,7 @@ use std::sync::{Arc, Mutex};
 use std::time::{Duration, SystemTime};
 
 use crate::events::Bus;
+use crate::{claude_credentials, paths};
 
 /// Returns the Claude credentials directory for this agent. Delegates
 /// to `paths::claude_dir`, which reads `$HOME/.claude`. The service
@@ -178,7 +179,25 @@ pub async fn wait_for_login(
     // re-trigger the fallback on every iteration.
     let baseline_unreadable = unreadable_mtime_names(claude_dir);
     let probe = Duration::from_millis(poll_ms.max(2000));
+    let pickup = swarm_pickup(claude_dir);
+    let mut next_pickup = tokio::time::Instant::now();
     loop {
+        if let Some(pickup) = &pickup
+            && tokio::time::Instant::now() >= next_pickup
+        {
+            next_pickup = tokio::time::Instant::now() + claude_credentials::POLL_INTERVAL;
+            match pickup.check().await {
+                Ok(claude_credentials::Outcome::Installed { version }) => tracing::info!(
+                    version,
+                    "installed the claude credentials the swarm login stored"
+                ),
+                Ok(outcome) => tracing::debug!(?outcome, "no newer swarm claude credentials"),
+                Err(e) => tracing::warn!(
+                    error = %format!("{e:#}"),
+                    "checking the swarm store for claude credentials failed"
+                ),
+            }
+        }
         tokio::time::sleep(probe).await;
         // A login that already landed by the time this first poll runs
         // (the race this baseline design closes) is caught here on the
@@ -193,6 +212,27 @@ pub async fn wait_for_login(
     }
 }
 
+/// The swarm-login pickup for `claude_dir`, or `None` when this process has
+/// no store to read from.
+fn swarm_pickup(
+    claude_dir: &Path,
+) -> Option<claude_credentials::Pickup<claude_credentials::Store>> {
+    match claude_credentials::Store::from_env() {
+        Ok(store) => Some(claude_credentials::Pickup::new(
+            store,
+            claude_dir.to_owned(),
+            paths::harness_dir().join(claude_credentials::VERSION_FILE),
+        )),
+        Err(e) => {
+            tracing::warn!(
+                error = %format!("{e:#}"),
+                "no swarm store coordinates, so a swarm login cannot reach this agent"
+            );
+            None
+        }
+    }
+}
+
 /// Names of credential files (see [`CRED_FILE_NAMES`]) currently present in
 /// `dir` whose mtime is *not* readable (`metadata()`/`modified()` errors —
 /// exotic fs, NFS quirks). Used once, at [`wait_for_login`]'s entry, as the