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

CHANGELOG.md

@@ -10,6 +10,26 @@ The long form, with what was wrong before and how it was found, is in
 
 ## [Unreleased]
 
+### Added
+
+- A Patreon token pasted into Add feed, or a creator's RSS link without `&show=`, becomes a folder
+  of that creator's shows, kept in step on every scan like a subscribed OPML. A creator with only
+  one show stays a plain feed. One already added as a single long feed is split into its shows on
+  its next scan, keeping its files and what you had read.
+- Add feed has an "Allow items marked explicit" box, so a new feed's first scan no longer skips
+  every explicit item.
+
+### Fixed
+
+- Turning on Allow explicit, or changing keywords or auto-download, brings back what those settings
+  had skipped on the feed's next scan. Before, an item was judged once, when first seen, and a
+  skipped one stayed skipped whatever you changed.
+- Feeds inside an OPML or a Patreon creator follow your settings on the folder unless you set their
+  own, as the folder's settings dialog said they did. Before, the folder's settings reached nothing
+  inside it.
+- A new feed no longer takes the name of one you removed earlier and shows that feed's old items.
+  Re-adding the same feed still gets its old name, and its history, back.
+
 ### Changed
 
 - The README is a short overview of what ipx does and how to run it, and points into `docs/` for