Drop FIREHOSE_JETSTREAM_URL override and fix scheduler preload
FIREHOSE_JETSTREAM_URL was redundant with JETSTREAM_URL — the firehose
worker just reads JETSTREAM_URL directly now.
Also scope the scheduler preload to `console` only. It was widened to
`['console', 'web']` during Phase 3 but the scheduler provider is only
registered for `console`, which caused a binding-resolution error when
`pnpm dev` booted the web server.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>