fix(wizard): use real EA2 flow/defines collections for steps

EA2's apply-batch doc collections are restricted to ['data','flow','rule',
'version','view']; there is no 'ea2_node'. Steps are themselves 'flow'
documents (kind='definition') linked to the parent flow via the 'defines'
edge collection with role='next' (or 'presentation').

handleStructureSave now does two batches:
1) create N step flows, capture server-assigned keys
2) wire parent->step1->...->stepN with create_edge on 'defines'

src/lib/wizardApi.ts

@@ -120,30 +120,37 @@ export const wizardApi = {
     return api.startTransaction(process_definition_id, business_subject, signal);
   },
 
-  /** Helpers so call sites don't have to know the discriminated-union shape by heart. */
   ops: {
-    createNode(flowKey: string, node: { _key: string; display_name: string; dispatch_kind: string; agent_capability?: string }): CreateOp {
-      const { _key, ...rest } = node;
+    createStep(node: { display_name: string; dispatch_kind: string; agent_capability?: string; description?: string }): CreateOp {
+      const name = node.display_name.toLowerCase().replace(/[^a-z0-9]+/g, "_").slice(0, 40) || "step";
       return {
         op: "create",
-        coll: "ea2_node",
-        data: { _key, flow_key: flowKey, ...rest },
+        coll: "flow",
+        data: {
+          kind: "definition",
+          name,
+          display_name: node.display_name,
+          status: "draft",
+          description: node.description || node.display_name,
+          source_context: "EA2_WIZARD_STEP",
+          dispatch_kind: node.dispatch_kind,
+          ...(node.agent_capability ? { agent_capability: node.agent_capability } : {}),
+        },
       };
     },
-    createEdge(_flowKey: string, fromKey: string, toKey: string, role = "next"): CreateEdgeOp {
-      // EA2 server rejects `data` on create_edge despite the OpenAPI schema marking it optional.
+    createStepEdge(parentFlowKey: string, childFlowKey: string): CreateEdgeOp {
       return {
         op: "create_edge",
-        edge_coll: "ea2_edge",
-        from: `ea2_node/${fromKey}`,
-        to: `ea2_node/${toKey}`,
-        role,
+        edge_coll: "defines",
+        from: `flow/${parentFlowKey}`,
+        to: `flow/${childFlowKey}`,
+        role: "next",
       };
     },
     publishFlow(flowKey: string): UpdateOp {
       return {
         op: "update",
-        coll: "ea2_flow",
+        coll: "flow",
         key: flowKey,
         data: { status: "published" },
       };