feat(workflows): add condition editor, loop controls, and edge visualization

Phase 2 frontend: visual condition editor with property rule builder, expression
input, message-type selector, loop toggle with max iterations, self-loop edge
rendering, conditional/loop edge badges, and per-edge validation display.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/renderer/components/WorkflowEditor.tsx

@@ -296,6 +296,7 @@ export function WorkflowEditor({
             onNodeRemove={handleNodeRemove}
             selectedEdgeId={selectedEdgeId}
             selectedNodeId={selectedNodeId}
+            validationIssues={issues}
             workflow={workflow}
           />
         </div>