Web dashboard v2 step 1: public summaries, legacy issue fallback

Public issue pages and the Atom feed now carry each pick's summary and
'Why it's here' line (bodies, The Brief, World Briefing and comments stay
private). Issues stored before issues.issue_json existed rebuild their
colophon and Behind the paper from issues.report_json / the run row and
candidate_runs, and recover the World Briefing chapter from the EPUB on
disk. The dev seed mirrors that legacy shape.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NHyYupFdBiR4VfoUM7NjSM

src/web/templates/issue_full.html

@@ -22,12 +22,12 @@
 <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>{{ colophon.entries_fetched }} from {{ colophon.feeds_seen }} feeds</dd>
-<dt>Candidates scored</dt><dd>{{ colophon.candidates }}</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 %} from n/a feeds{% 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>{{ colophon.cost_usd }}</dd>
+<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>
 </article>{% endblock %}