feat(FN-1850): aggregate projects across connected nodes

- Add /api/projects/across-nodes to merge local projects with online remote node project lists
- Expose fetchProjectsAcrossNodes and ProjectInfoWithSource, and switch useProjects to consume cross-node data
- Update ProjectOverview and ProjectCard with node badges, node count stats, and a node filter dropdown plus responsive styles
- Add server and dashboard test coverage for cross-node aggregation, filtering, and hook behavior changes
- Include a changeset for @gsxdsm/fusion minor release and preserve stale-channel SSE reconnect guards during merge

packages/dashboard/app/api.ts

@@ -3280,6 +3280,17 @@ export function fetchProjects(): Promise<ProjectInfo[]> {
   return api<ProjectInfo[]>("/projects");
 }
 
+/** Project info with source node metadata (added by server for remote projects) */
+export interface ProjectInfoWithSource extends ProjectInfo {
+  /** Name of the source node (added by server for remote projects) */
+  _sourceNodeName?: string;
+}
+
+/** Fetch all registered projects from all nodes (local + remote) */
+export function fetchProjectsAcrossNodes(): Promise<ProjectInfoWithSource[]> {
+  return api<ProjectInfoWithSource[]>("/projects/across-nodes");
+}
+
 /** Fetch all registered nodes */
 export function fetchNodes(): Promise<NodeInfo[]> {
   return api<NodeInfo[]>("/nodes");