feat: full UI overhaul — dark theme with custom design system

Replace Pico CSS with a custom dark design system:
- Deep navy background (#090b12) with violet-indigo accent (#7b6cf5)
- Outfit font for UI, JetBrains Mono for code/URLs
- Custom nav with SVG icons and active-state highlighting
- Pill badges with colored status dots
- Uppercase letter-spaced table headers
- Stat cards on replica detail page
- h3 section headings with extending rule line
- Refined dialog/modal styling with blur backdrop
- Terminal-style SSE log stream
- Progress bar with accent gradient animation
- Page entrance fade-in animation
- All Pico CSS variable references replaced with custom tokens

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

app/templates/partials/log_table.html

@@ -13,11 +13,11 @@
   <tbody>
     {% for log in logs %}
     <tr class="log-entry-{{ log.level or 'info' }}">
-      <td><small>{{ log.created_at.strftime('%Y-%m-%d %H:%M:%S') if log.created_at else '' }}</small></td>
+      <td><small style="font-family:var(--mono);">{{ log.created_at.strftime('%Y-%m-%d %H:%M:%S') if log.created_at else '' }}</small></td>
       <td><span class="badge badge-{{ log.level or 'info' }}">{{ log.level or 'info' }}</span></td>
-      <td>{{ log.replica_id or '' }}</td>
-      <td>{{ log.doc_id or '' }}</td>
-      <td>{{ log.message or '' }}</td>
+      <td style="font-size:.82rem;">{{ log.replica_id or '' }}</td>
+      <td style="font-family:var(--mono); font-size:.8rem;">{{ log.doc_id or '' }}</td>
+      <td style="font-size:.83rem;">{{ log.message or '' }}</td>
     </tr>
     {% endfor %}
   </tbody>