Fix stray promo headers, site-URL subscribing, and YouTube playback

Three reported bugs.

**"West Hawaii today articles get a bunch of stray Trending headers."**
The publisher's widget platform injects promo blocks between the real
paragraphs, inside the article's own container, so every structural
signal tells Readability they belong. What survives is a heading
labelling nothing, because the links under it are filled in by a script
that never runs in the reader. Confirmed on 9 of the 12 articles in
that feed, two each. Blocks marked `data-mrf-recirculation` are now
removed -- the attribute says what the block is for in the widget
platform's own words, which is a better signal than the word
"Trending", since an article may legitimately discuss what is trending.
Nothing longer than a label and a few headlines is ever removed. Also
applied to already-cached articles, in place rather than by discarding
them: the article was fine, only the litter has to go.

**"Can't subscribe to heathercoxrichardson.substack.com."** Adding a
feed handed whatever URL it was given straight to the XML parser, so a
site's home page -- the only URL a reader can actually see and copy --
failed on the root element. That page advertises its feed the way sites
have since 2002, in a <link rel="alternate"> in the head. It is now
read, resolved against the page, and fetched. Only what the page
declares: guessing /feed and /rss would add a burst of 404s to every
failed add and eventually subscribe somebody to the wrong thing.

**"YouTube play is misconfigured."** It was, and YouTube said so: the
player dialog loaded the embed as its own top-level document, which
answers with "Video player configuration error -- Error 153". An embed
has to be embedded. It now sits in an iframe on a minimal host page.
Measured in the app's own WebView: top-level, no requests for the video
stream and the error on screen; framed, the stream loads and there is
no error.

**"Long click on YouTube placeholder should open the URL directly."**
It does now. Worth recording why this is not simply the link's href:
for an image inside a link, WebView's hit test reports the image's URL,
so a long-press on the thumbnail arrives as the i.ytimg.com JPEG. The
video id is resolved out of that.

Verified on a device for all four: the Substack site URL adds "Letters
from an American" and fetches 20 articles; a West Hawaii Today article
extracts with no Trending headers and its body intact; the video plays;
and a long-press reaches the YouTube app.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018AwnALZL6bD4VBtATDVv3B

1 files changed, 14 insertions, 0 deletions

diff --git a/BACKLOG.md b/BACKLOG.md
index 2918517..bb7f075 100644
--- a/BACKLOG.md
+++ b/BACKLOG.md
@@ -51,6 +51,20 @@ doesn't just hand off to the YouTube app/browser as originally planned —
 dialog, main-frame navigation locked to YouTube's own domains), so watching
 a video doesn't leave the reader.
 
+**Fixed 2026-10-21, reported as "YouTube play is misconfigured":** the dialog
+loaded the embed as its own top-level document, and YouTube answers that with
+"Video player configuration error -- Error 153". An embed has to be embedded;
+it now sits in an `<iframe>` on a minimal host page (`YouTubeLinks`). Measured
+in the app's own WebView, before and after: top-level, 0 requests for the video
+stream and the error on screen; framed, 8 stream requests and no error.
+
+**Added at the same time:** a long-press on the thumbnail opens the video in
+the YouTube app instead of the link-actions menu. A tap already plays it in the
+reader, so a long-press has only one useful meaning. Note that WebView reports
+the *thumbnail's* URL for a long-press on an image inside a link, not the
+link's href -- `youTubeTargetForLongPress` resolves the video id out of the
+`i.ytimg.com/vi/<id>/` path.
+
 ## Bottom action strip (partially done)
 
 **Done:** swipe-to-next-article dropped entirely (two different attempts at