Show what the pipeline understood about each article

A muted one-line note now follows every article: the deep assessment's
topic group, format, depth and technicality, the specific topics it
extracted, and the reader interests the article matched best, e.g.

  Software engineering · analysis essay · in depth · highly technical ·
  Topics: copy-on-write, ZFS · Interests: Filesystems, Rust

It renders on the web article page footer, on the public and private
issue-page entries, in the EPUB article footer and in the EPUB "In This
Issue" index (both editions), always styled like the existing meta lines
so it stays secondary to the content.

`Pick` gains `top_interests` (serde default, no migration), filled from
the signals stage when the editor assembles the lineup; the facets were
already on the issue snapshot via `Pick.llm`, so earlier issues show the
facet and topic parts and only future issues carry interests. One shared
builder, `understanding_line` in epub::chapters, feeds every surface.

The dev seed gives four picks facets and interests so the line can be
eyeballed locally.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QVPagF6jfDv78CC5Jv2wp4

src/web/templates/issue_full.html

@@ -5,7 +5,7 @@
   <section aria-labelledby="brief-heading" data-toc-entry="/issues/{{ date }}"><h1 id="brief-heading" class="reader-section-heading">The Brief</h1><div class="editorial prose-body mt-5 [&>p:first-child]:first-letter:float-left [&>p:first-child]:first-letter:mr-2 [&>p:first-child]:first-letter:mt-1 [&>p:first-child]:first-letter:font-serif [&>p:first-child]:first-letter:text-[4.6rem] [&>p:first-child]:first-letter:font-semibold [&>p:first-child]:first-letter:leading-[0.72]">{{ front_page_html|safe }}</div></section>
   {% if (page.is_admin() && read_href.is_some()) || downloads.is_some() %}<div class="my-8 flex flex-wrap gap-2 border-y border-rule py-4">{% if page.is_admin() %}{% match read_href %}{% when Some with (href) %}<a class="btn" href="{{ href }}" target="_blank" rel="noopener">Read in BookOrbit</a>{% when None %}{% endmatch %}{% endif %}{% match downloads %}{% when Some with (downloads) %}{% if downloads.others.is_empty() %}<a class="btn" href="{{ downloads.primary.href }}">Download {{ downloads.primary.label }}</a>{% else %}<div class="relative inline-flex"><a class="btn rounded-r-none" href="{{ downloads.primary.href }}">Download {{ downloads.primary.label }}</a><details class="-ml-px"><summary class="btn list-none rounded-l-none px-2 [&::-webkit-details-marker]:hidden" aria-label="Choose download format"><span aria-hidden="true">▾</span></summary><div class="absolute left-0 top-full z-20 mt-1 min-w-52 border border-rule bg-paper p-1 shadow-[0_18px_32px_-26px_rgb(0_0_0_/_0.6)]"><a class="btn group w-full justify-between border-0" href="{{ downloads.primary.href }}"><span>{% if downloads.primary.label == "EPUB" %}Standard {% endif %}{{ downloads.primary.label }}</span><span class="ml-4 text-muted group-hover:text-paper">{{ downloads.primary.size }}</span></a>{% for download in downloads.others %}<a class="btn group w-full justify-between border-0" href="{{ download.href }}"><span>{{ download.label }}</span><span class="ml-4 text-muted group-hover:text-paper">{{ download.size }}</span></a>{% endfor %}</div></details></div>{% endif %}{% when None %}{% endmatch %}</div>{% endif %}
   <section class="mt-12" aria-labelledby="index-heading"><h2 id="index-heading" class="text-center text-3xl font-semibold leading-[1.1] tracking-[-0.01em]">In This Issue</h2>
-    {% for section in sections %}<section class="mt-14"><h3 class="reader-section-heading">{{ section.name }}</h3><ul class="m-0 list-none p-0">{% for entry in section.entries %}<li class="border-b border-rule py-6" data-toc-entry="{{ entry.href }}"><h4 class="font-serif font-semibold leading-[1.1] tracking-[-0.01em] {% if entry.is_lead %}text-3xl{% else %}text-2xl{% endif %}"><a class="text-ink no-underline hover:text-accent" href="{{ entry.href }}">{{ entry.title }}</a></h4><p class="mt-2 font-sans text-sm text-muted">{{ entry.source }} · {{ entry.reading_minutes }} min read{% if page.is_admin() %} · <a class="text-muted hover:text-accent" href="{{ entry.dashboard_href }}">dashboard</a>{% endif %}</p>{% if !entry.summary.is_empty() %}<p class="index-summary mt-4">{{ entry.summary }}</p>{% endif %}{% match entry.why %}{% when Some with (why) %}<p class="mt-4 border-l-2 border-accent pl-3 italic text-ink-2">Why it's here: {{ why }}</p>{% when None %}{% endmatch %}{% match entry.rating %}{% when Some with (widget) %}{% include "_rating_widget.html" %}{% when None %}{% endmatch %}</li>{% endfor %}</ul></section>{% endfor %}
+    {% for section in sections %}<section class="mt-14"><h3 class="reader-section-heading">{{ section.name }}</h3><ul class="m-0 list-none p-0">{% for entry in section.entries %}<li class="border-b border-rule py-6" data-toc-entry="{{ entry.href }}"><h4 class="font-serif font-semibold leading-[1.1] tracking-[-0.01em] {% if entry.is_lead %}text-3xl{% else %}text-2xl{% endif %}"><a class="text-ink no-underline hover:text-accent" href="{{ entry.href }}">{{ entry.title }}</a></h4><p class="mt-2 font-sans text-sm text-muted">{{ entry.source }} · {{ entry.reading_minutes }} min read{% if page.is_admin() %} · <a class="text-muted hover:text-accent" href="{{ entry.dashboard_href }}">dashboard</a>{% endif %}</p>{% if !entry.summary.is_empty() %}<p class="index-summary mt-4">{{ entry.summary }}</p>{% endif %}{% match entry.why %}{% when Some with (why) %}<p class="mt-4 border-l-2 border-accent pl-3 italic text-ink-2">Why it's here: {{ why }}</p>{% when None %}{% endmatch %}{% match entry.understanding %}{% when Some with (line) %}<p class="mt-3 font-sans text-sm text-muted">{{ line }}</p>{% when None %}{% endmatch %}{% match entry.rating %}{% when Some with (widget) %}{% include "_rating_widget.html" %}{% when None %}{% endmatch %}</li>{% endfor %}</ul></section>{% endfor %}
   </section>
   {% if has_world || has_behind %}<nav class="my-12 flex flex-wrap items-center justify-center gap-x-3 gap-y-1 border-y border-rule py-4 text-center font-sans text-sm uppercase tracking-[0.08em]" aria-label="Issue chapters">{% if has_world %}<a class="text-ink no-underline hover:text-accent" href="/issues/{{ date }}/world">World Briefing</a>{% endif %}{% if has_world && has_behind %}<span class="text-muted" aria-hidden="true">·</span>{% endif %}{% if has_behind %}<a class="text-ink no-underline hover:text-accent" href="/issues/{{ date }}/behind">Behind the paper</a>{% endif %}</nav>{% endif %}
   <footer id="colophon" class="mt-14 scroll-mt-6 font-sans text-sm leading-relaxed" data-toc-entry="/issues/{{ date }}#colophon"><h2 class="reader-section-heading">Colophon</h2><p class="my-4 text-ink-2"><em>The Daily EPUB</em> is assembled every morning from a personal feed reader.</p><dl class="kv border-y border-rule py-4 text-xs sm:text-sm"><dt>Generated</dt><dd>{{ colophon.generated_at }}</dd><dt>Bulk model</dt><dd>{{ colophon.bulk_model }}</dd><dt>Editor model</dt><dd>{{ colophon.editor_model }}</dd><dt>Summaries model</dt><dd>{{ colophon.summaries_model }}</dd><dt>Entries considered</dt><dd>{% match colophon.entries_fetched %}{% when Some with (entries) %}{{ entries }}{% match colophon.feeds_seen %}{% when Some with (feeds) %} from {{ feeds }} feeds{% when None %}{% endmatch %}{% when None %}n/a{% endmatch %}</dd><dt>Candidates scored</dt><dd>{% match colophon.candidates %}{% when Some with (candidates) %}{{ candidates }}{% when None %}n/a{% endmatch %}</dd><dt>Articles selected</dt><dd>{{ colophon.article_count }} across {{ colophon.section_count }} sections</dd><dt>Words</dt><dd>{{ colophon.total_words }} · ~{{ colophon.reading_minutes }} min read</dd>{% for cost in colophon.provider_costs %}<dt>{{ cost.provider }} cost</dt><dd>{{ cost.cost }}</dd>{% endfor %}<dt>Total token cost</dt><dd>{% match colophon.cost_usd %}{% when Some with (cost) %}{{ cost }}{% when None %}n/a{% endmatch %}</dd><dt>Generator</dt><dd>{{ colophon.generator_version }}</dd></dl></footer>