The agent-facing endpoint becomes derived rather than `otel.endpoint`
re-defined: with the collector on, agents and hive-c0re's own exporter
send to the bridge address; with it off the expression is the old value
character for character. `otel.endpoint` keeps meaning "where telemetry
ultimately goes" on every hive that already sets it.
Suppressing HYPERHIVE_OTEL_HEADERS_CREDENTIAL is the half that actually
closes the hole this issue is about. The credential path host -> container
is sound (/run/credentials is dr-x------ root), but the hive-otel-header
oneshot then writes the value into the agent's own settings.json, mode
0600 and owned by the agent — so today every agent can read the hive's
upstream telemetry credential. With a collector there is nothing to
forward.
The protocol is derived for the same reason the endpoint is: the first
hop is now the collector's OTLP/HTTP receiver, while otel.protocol
describes the upstream link.