Every agent now connects to the queue and reads logs with its own secret
from the store (#5181), so the per-hive `hive-<h>-agent` OIDC client has
no reader left. Remove it end to end:
- hive-c0re no longer forwards `hive-queue-agent-{secret,client-id}` into
containers, and no longer forwards HIVE_AGENT_OIDC_TOKEN_ENDPOINT; the
agent module that loaded them (nix/agent-modules/queue.nix) is gone, its
options refused with a removal message.
- The host reader (glue-queue-agent-credential.nix, swarm-bao-queue-agent),
its store role and policy unit (swarm-bao-queue-agent-policy), its PKI
leaf and the deploy.bao.queueAgent* / queue.agentCredentialDir options
are gone; the options are refused with a removal message.
- authelia mints no `hive-<h>-agent` client, and swarm-secret-publish no
longer writes swarm/hives/<h>/queue/agent.
- swarm-secret-client drops queue::agent_client_path / queue::Credential.
- HIVE_AGENT_NATS_URL is now gated on the agents' queue address alone.
The log store's authelia check stays for operators. swarm-nats-auth still
refuses a `-agent` client id; that refusal and `agentClientSuffix` are left
for a follow-up.
Refs #4459
Refs #4765
868c6cf96c