Add Share to L2 buttons for media, recipes, and runs

- Updated cache detail button from "Publish to IPFS" to "Share to L2"
- Added Share to L2 button on recipe detail page
- Added Share to L2 button on run detail page
- Created /recipes/{id}/publish endpoint
- Created /runs/{id}/publish endpoint (publishes run output)

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

app/templates/runs/detail.html

@@ -22,6 +22,13 @@
         {% if run.cached %}
         <span class="bg-purple-900 text-purple-300 px-3 py-1 rounded text-sm">Cached</span>
         {% endif %}
+        <div class="flex-grow"></div>
+        <button hx-post="/runs/{{ run.run_id }}/publish"
+                hx-target="#share-result"
+                class="bg-purple-600 hover:bg-purple-700 px-3 py-1 rounded text-sm font-medium">
+            Share to L2
+        </button>
+        <span id="share-result"></span>
     </div>
 
     <!-- Info Grid -->