One article header everywhere: rubric, why block, then the summary

The web index, the article page and both EPUB pages each ordered the same
metadata differently, and the "understanding" line was one wall of text
with the why line above it on one page and below it on another. Every
surface now reads title, meta, rubric, why block, summary:

- the rubric is a newspaper kicker (topic group and format in small caps)
  followed by the specific topics; depth and technicality stay on the
  dashboard article page only
- the accent-bar why block holds the editor's line and "Matches: …" (the
  matched interests) beneath it
- the social line moves after the summary on the article page and chapter,
  matching the index pages, and the EPUB chapter footer no longer carries
  the understanding line

`understanding_line` becomes an `Understanding { kicker, topics, interests }`
struct shared by the web view models and the EPUB, and the three web
templates include one `_understanding.html` partial.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NxctvrEPQZ9pX58LRgGYNZ

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">{% match entry.author %}{% when Some with (author) %}{{ author }} · {% when None %}{% endmatch %}{% let source = entry.source %}{% include "_source.html" %} · {{ 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 %}
+    {% 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">{% match entry.author %}{% when Some with (author) %}{{ author }} · {% when None %}{% endmatch %}{% let source = entry.source %}{% include "_source.html" %} · {{ entry.reading_minutes }} min read{% if page.is_admin() %} · <a class="text-muted hover:text-accent" href="{{ entry.dashboard_href }}">dashboard</a>{% endif %}</p>{% let understanding = entry.understanding %}{% let why = entry.why %}{% include "_understanding.html" %}{% if !entry.summary.is_empty() %}<p class="index-summary mt-4">{{ entry.summary }}</p>{% endif %}{% 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>