Re-derivation of #33612 by @LeonSGP43 onto the rewritten scheduler (the
original is 10,692 commits behind; its tick() no longer exists in that
shape, so this is a fresh minimal fix crediting the PR's idea).
The gateway's built-in ticker calls tick(verbose=False) every 60s. The
idle early-return was gated on 'verbose and not due_jobs', so idle
GATEWAY ticks fell through to load_config() + worker-pool resolution
every minute. Return early on ANY idle tick; keep the post-tick MCP
orphan sweep (main intentionally reaps orphaned stdio children on idle
ticks).
3 new tests; mutation-checked (restoring the verbose-gated guard fails
the config-skip test). 66 scheduler tests green.
