feat: let the operator set the daily comment limit per account

The allowance was derived from the adaptive trust level with no way to
change it, which made the dashboard's "1 / 2 today" unexplainable and
left no way to slow an account down or push one along.

`dailyLimit` is null by default, keeping today's adaptive behaviour. A
whole number between 1 and 50 overrides it and is enforced verbatim in
either direction — it can raise an account above what it has earned or
hold it below. The trust level keeps being tracked underneath and is
reported as `adaptiveAllowance`, so the earned figure stays visible next
to the override, and clearing the field hands pacing back to the ladder.

Raising the limit above the earned allowance does remove the adaptive
backoff after a bad comment, so the dashboard says exactly that where the
limit is set. It does not touch the pause on two consecutive removals, a
comment the public cannot see, or a captcha challenge: those are safety
stops rather than rate controls and no limit setting can disable them.

Also correct two things the page was saying badly. The allowance is now
labelled "used in last 24h" with the trust level shown as what it earns,
because it is a rolling window and not a midnight reset. And a
per-community cap above the account allowance now states how much of it
is actually reachable — "1 of 10 today" beside an account limit of 2 read
as far more headroom than existed, since caps distribute the allowance
rather than adding to it.

Verified against a local instance: override above and below the earned
allowance, unrelated saves preserving it, clearing it through the UI,
rejection of 0/51/2.5/non-numeric, and a limit failing to clear a pause.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/database.md

@@ -17,7 +17,7 @@ The application uses one `better-sqlite3` database, normally `data/reddit-bot.db
 - `reddit_media`: account-scoped private-media metadata and relative file path.
 - `media_library_assets`: process-global operator-owned image metadata, overlapping anatomy tags, SFW/NSFW classification, consent time, enablement, dimensions, hash, and private relative path.
 - `media_library_sends`: account/conversation/inbound-event reservation and confirmed/failed Matrix delivery audit for a shared library asset.
-- `account_growth_settings`: per-account commenting switch, adaptive trust level, spacing/jitter, quiet hours, NSFW opt-in, and the operator-clearable pause reason.
+- `account_growth_settings`: per-account commenting switch, adaptive trust level, optional operator daily-limit override (`daily_limit`, null means adaptive), spacing/jitter, quiet hours, NSFW opt-in, and the operator-clearable pause reason.
 - `account_growth_subreddits`: per-account community list with weight, daily cap, and any Reddit-imposed disable reason or cooldown.
 - `account_growth_comments`: durable growth comment records from discovery through posting and verification, including the exact text posted, score history, removal and public-visibility verdicts.