#4636 Docs: swamp serve reload now applies scheduling, the scheduled-run limit and timed-service on/off

Once swamp-club#4633 ships, swamp serve reload applies schedule and max-concurrent-scheduled-runs, and turns serve's timed services on or off (group refresh, server token GC, the continuation sweep, the webhook routes poller) without a restart. A lowered interval for group refresh, token GC, the sweep or reconciliation also takes effect at once instead of after the timer already set. These manual pages describe the old behaviour:

• content/manual/reference/swamp-serve/serve-flags.md
  • --max-concurrent-scheduled-runs: "Read at startup, not on reload." → applied by swamp serve reload; a raised limit starts queued scheduled runs at once, a lowered one never stops a run in flight.
  • --webhook-routes-poll: "Set at startup only, not on reload." → a reload turns the poller on or off and changes its interval.
  • The schedule / --no-schedule entry: add that a reload turns scheduling on or off. Turning it off stops new fires and keeps queued runs pending for replay; runs already in flight finish. In team mode, catch-up runs only on the leader.
• content/manual/how-to/run-workflows-on-a-schedule.md: "Serve reads the value at startup; restart serve to change it." → change it in serve.yaml and run swamp serve reload.
• content/manual/reference/swamp-serve/hot-reload.md and content/manual/how-to/swamp-serve/reload-extensions-without-restart.md: list scheduling, the scheduled-run limit and the timed services among what a reload applies. Settings that still need a restart: the listener, the auth mode and the datastore. The continuation sweep also still needs one on a datastore where it runs only at boot, or where it has no shared claims.

Write it after #4633 merges, so the wording matches what shipped.