On first boot (or after a wipe) hive-c0re writes forge-core-token only
after the forge container starts and the admin is provisioned. This
lags hive-c0re.service becoming active. The previous code bailed
immediately with TOKEN=placeholder if the token file was absent,
causing the runner to fail registration with 'token not found'.
Fix: merge both waits (core-token file appearance + forge API ready)
into a single 60s retry loop. The early-bail path is removed; the
script only exits cleanly if .runner is valid (writes placeholder)
or a fresh registration token is obtained.
When .runner exists but core-token is absent after 60s, we keep the
existing credentials (safe — the runner holds valid creds; next boot
will validate properly).
Closes#1224 (which tracks #1221).
dacd83f278