feat: autolink URLs in list items, link picker, and inline edit

- Add autolink Jinja2 filter to detect URLs and make them clickable
- Add link picker dropdown to insert existing link URLs into list item content
- Add inline edit with link picker on each list item row
- Apply autolink filter on list detail and focus available list items

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

templates/focus.html

@@ -139,7 +139,7 @@
         {% for li in available_list_items %}
         <div class="list-row{% if loop.index > 25 %} focus-hidden-item hidden{% endif %}" style="padding:3px 8px;min-height:0;">
             <span style="color:var(--muted);font-size:0.85rem;margin-right:4px">&#9776;</span>
-            <span class="row-title">{{ li.content }}</span>
+            <span class="row-title">{{ li.content|autolink }}</span>
             {% if li.list_name %}<span class="row-tag" style="background:var(--purple);color:#fff">{{ li.list_name }}</span>{% endif %}
             <form action="/focus/add" method="post" style="display:inline">
                 <input type="hidden" name="list_item_id" value="{{ li.id }}">