feat(executor): node pinned_input overrides upstream byPort on manual runs

src/VolcanicCore.Api/Engine/Executor.cs

@@ -183,6 +183,16 @@ public sealed class Executor
                 }
 
                 var byPort = BuildInputsByPort(portMap, allowFailurePlaceholders: false);
+
+                // Manual runs honor the node's pinned_input — replaces byPort[0] with the
+                // pinned items. Node's own logic still runs (we intentionally don't skip
+                // upstream ancestors; their output is discarded for THIS node's byPort).
+                if (triggerKind == "manual" && node.PinnedInputJson is { } nodePinJson)
+                {
+                    using var pinDoc = JsonDocument.Parse(nodePinJson);
+                    byPort = new IReadOnlyList<Item>[] { WrapPin(pinDoc.RootElement) };
+                }
+
                 var typ = _nodes.Get(node.TypeId);
                 if (typ is not IActionNode action)
                     throw new InvalidOperationException($"Node {nid} is not an action type.");