Add artifacts to run detail view

Build artifacts list from run output_hash and detect media type
for display in the artifacts tab.

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

app/routers/runs.py

@@ -140,10 +140,30 @@ async def get_run(
             except Exception as e:
                 logger.warning(f"Failed to load recipe for plan: {e}")
 
+        # Build artifacts list from output and inputs
+        artifacts = []
+        if run.get("output_hash"):
+            # Detect media type
+            output_hash = run["output_hash"]
+            media_type = None
+            try:
+                cache_path = get_cache_manager().get_path(output_hash)
+                if cache_path and cache_path.exists():
+                    import mimetypes
+                    media_type, _ = mimetypes.guess_type(str(cache_path))
+            except Exception:
+                pass
+            artifacts.append({
+                "hash": output_hash,
+                "step_name": "Output",
+                "media_type": media_type or "application/octet-stream",
+            })
+
         templates = get_templates(request)
         return render(templates, "runs/detail.html", request,
             run=run,
             plan=plan,
+            artifacts=artifacts,
             active_tab="runs",
         )