fix(activity): runs keep their true outcome and spend, the page reaches every kept row, a closing dialog leaves the server log alone

Backend
- A run's outcome write sits outside the job's own try: a database blip after a run that
  succeeded no longer records it as failed (the row waits for the next start's sweep).
- An interrupted run keeps what it spent (the sweep sums its quota rows, as finish does).
- The Scheduler's ad-hoc row says running while any backfill runs, not only the newest.
- recent_runs reads each job's last runs off its index instead of ranking the whole table.
- An interval change is stored with its audit row in one transaction, then rescheduled.
- One API instance per database is the stated contract (.env.example, jobruns).
- Turning full history on for a channel already complete records no run.
- Migration 0109 round-trips interrupted and ad-hoc runs; the run words' DB CHECKs are
  test-held to the enums; the account filter is one helper for the four activity reads.
- An audit row says how many of its request's log lines are still kept.

Frontend
- An "All" period reaches every row still kept (runs and admin actions outlive 90 days).
- Back/Forward is followed in place by the server log: a closing dialog no longer turns
  Live off; a pivot still opens a fresh log.
- Runs moved over from the audit log read their one-liner in the reader's language.
- Filter choices or accounts that failed to load say so beside the filters, with a retry.
- An old server-log link keeps its account, text and range; a remembered retired page
  opens its tab.
- A request whose lines are gone says so instead of linking to an empty list.
- The log lines and the history rows share one row frame, and the server log one list
  frame with the other tabs; an empty list is announced; each day's quota is readable.

backend/app/routes/channels.py

@@ -512,7 +512,9 @@ def update_channel(
     # so the whole catalogue lands in seconds instead of over the scheduler's paced 10-minute ticks.
     # The request returns right away; the channel page's live poll shows the count climb. The
     # scheduler still finishes a very large channel's tail on its normal runs (deep_requested stays set).
-    if deep_turned_on:
+    # A channel whose history is all in gets no run: it would only say "nothing to do", one kept row
+    # per flip of the flag.
+    if deep_turned_on and not (channel is not None and channel.backfill_done):
         scheduler.run_ad_hoc(
             scheduler.CHANNEL_BACKFILL,
             partial(backfill_channel_now, channel_id, user.id),