Show download date and watch status on Admin rows

Surfaces the download-age cutoff data (already computed for the 6-month
filter) directly on each row, plus an explicit "Never watched" label, so
the never-watched call behind the delete button is visible rather than
just trusted.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LPJxtE9tPURsaWDZ6rC4Dt

templates/system.html

@@ -186,7 +186,7 @@
         <span class="tt-row-name">{{ show.ep_count }} EP</span>
         <span class="tt-row-body">
           <span class="tt-row-title">{{ show.title }}</span>
-          {% if show.year %}<span class="tt-row-sub">{{ show.year }}</span>{% endif %}
+          <span class="tt-row-sub">{% if show.year %}{{ show.year }} &middot; {% endif %}Downloaded {{ show.added[:10] if show.added else 'unknown' }} &middot; Never watched</span>
         </span>
         <span class="tt-row-val">{{ show.size_display }}</span>
         <span class="tt-row-acts">