rc1: clickhouse read replica routing + run detail nav (PR #4081)

rc0: clickhouse read replica routing (PR #4081)

chore: switch build jobs to blacksmith

fix: blacksmith testbox test scripts (#4074)

fix(supervisor): scrape timeout + schema-level pod-count hysteresis g…

…uard

fix(supervisor): scrape apiserver /metrics over https so TLS verifies…

… against the cluster CA

fix(supervisor): scrape timeout + schema-level pod-count hysteresis g…

…uard

test(run-engine): keep worker queue observation test lean to avoid CI…

… timeout

Disable the execution workers and batch consumers in the worker queue
observation test. It only needs enqueue + processMasterQueue + the observer
gauge, and the extra workers add Redis connections and make engine.quit()
hang on worker shutdown when the shard's Redis is under pressure, timing the
test out in CI.

feat(webapp): gate worker dequeues by worker queue via env var

Add RUN_ENGINE_DEQUEUE_DISABLED_WORKER_QUEUES: a comma-separated list of
worker queues (or base regions, which also cover the :scheduled split) for
which the engine API refuses worker dequeue requests and returns no work, so
those runs stay queued instead of being handed to workers that cannot run
them. Unset means no gating. Blocked dequeues increment the
run_engine.dequeue.blocked otel counter, tagged by worker_queue and region.

feat(webapp): add region override to the bulk replay action

When replaying runs in bulk from a deployed environment, you can now choose
which region the replayed runs run in. The inspector shows an "Override
region" dropdown that defaults to "Don't override", which keeps each run in
its original region, so replaying a selection that spans multiple regions
doesn't silently re-route anything. Pick a region and every matched run is
replayed there instead.