Patreon creators split into their shows; filters follow settings

A Patreon token pasted into Add feed, or a creator link without
&show=, becomes a folder of that creator's shows, found through
Patreon's web API and kept in step like a subscribed OPML (sync_group,
split out of sync_opml). A creator already read as one feed is split
too: each show takes over the files and read state it held
(Db::adopt). A creator with one show stays a plain feed.

Filter verdicts are judged again every scan, so turning on Allow
explicit brings skipped items back. Add feed has an explicit box.
Feeds in a group follow your settings on the group, as its dialog
said. A new feed no longer takes the id of a removed one at a
different URL and shows its old items. See CHANGELOG.md [Unreleased]
and docs/history.md.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wi22VSVrkAvqNj61eqHsm9

docs/architecture.md

@@ -28,12 +28,15 @@ The page is compiled in, so **editing `web/index.html` needs a rebuild**.
 1. Skip the feed unless `last_checked + max(schedule, ttl)` has passed (`--force` ignores this).
 2. Conditional GET with the stored `ETag` / `Last-Modified`. `304` ends it there.
 3. Sniff the body: RSS, then Atom, then OPML. An OPML is a live subscription — its feeds are
-   re-derived into the database each scan, never written to config.toml.
+   re-derived into the database each scan, never written to config.toml. A Patreon creator link
+   (a token, no `show=`) with more than one show is treated the same way, before any fetch: its
+   shows come from Patreon's web API and each becomes a derived feed.
 4. Record entries. A changed title or description flips the item back to unread.
 5. Record enclosures. `enclosures.url` is `UNIQUE`, which is the dedupe key and subsumes the
    original's `history.dat` pickle: a reaped file keeps its row so it is never fetched twice.
 6. Apply the merged policy (see [users.md](users.md)) and mark anything rejected as `skipped` with
-   a reason.
+   a reason. What a filter skipped is judged again every scan, so a change of settings brings it
+   back. A feed in a group takes your settings on the group for anything you have not set on it.
 7. Download what is still pending, newest first, up to the per-scan cap. A `.torrent` body goes to
    the torrent path whatever its advertised type; an HTML body is a failed download — a login wall
    or an error page — and is deleted.