Fix MP4 mux for web playback: add faststart and genpts

- Add -movflags +faststart to move moov atom to start
- Add -fflags +genpts for proper timestamp generation
- Fixes jerky playback and video/audio desync

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/templates/runs/detail.html

@@ -575,7 +575,7 @@
         {# Inline media preview - prefer IPFS URLs when available #}
         <div class="mb-4">
             {% if output_media_type and output_media_type.startswith('image/') %}
-            <a href="/cache/{{ run.output_cid }}" class="block">
+            <a href="{% if run.ipfs_cid %}/ipfs/{{ run.ipfs_cid }}{% else %}/cache/{{ run.output_cid }}{% endif %}" class="block">
                 <img src="{% if run.ipfs_cid %}/ipfs/{{ run.ipfs_cid }}{% else %}/cache/{{ run.output_cid }}/raw{% endif %}" alt="Output"
                      class="max-w-full max-h-96 rounded-lg mx-auto">
             </a>
@@ -593,14 +593,15 @@
         </div>
 
         <div class="flex items-center justify-between">
-            <a href="/cache/{{ run.output_cid }}" class="font-mono text-sm text-blue-400 hover:text-blue-300">
-                {{ run.output_cid }}
+            <a href="{% if run.ipfs_cid %}/ipfs/{{ run.ipfs_cid }}{% else %}/cache/{{ run.output_cid }}{% endif %}"
+               class="font-mono text-sm text-blue-400 hover:text-blue-300">
+                {% if run.ipfs_cid %}{{ run.ipfs_cid }}{% else %}{{ run.output_cid }}{% endif %}
             </a>
             {% if run.ipfs_cid %}
             <a href="https://ipfs.io/ipfs/{{ run.ipfs_cid }}"
                target="_blank"
                class="text-gray-400 hover:text-white text-sm">
-                IPFS: {{ run.ipfs_cid[:16] }}...
+                View on IPFS Gateway
             </a>
             {% endif %}
         </div>