feat(FN-3079): add plugin dashboard views and dependency graph plugin

- Add plugin dashboard view registration and hosting across core, dashboard routes, and plugin SDK exports
- Integrate plugin-provided views into app navigation, mobile/header UI, and view state hooks with coverage
- Add fusion-plugin-dependency-graph example plugin with persisted storage, dashboard view UI, and manifest wiring
- Update plugin authoring and architecture docs for dashboard view extension points
- Add a changeset for @runfusion/fusion covering plugin dashboard view support

Fusion-Task-Id: FN-3079

packages/dashboard/app/plugins/pluginViewRegistry.css

@@ -0,0 +1,27 @@
+.plugin-dashboard-view-missing {
+  margin: var(--space-lg);
+  padding: var(--space-lg);
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-md);
+}
+
+.plugin-dashboard-view-missing-title {
+  margin: 0;
+  display: flex;
+  align-items: center;
+  gap: var(--space-sm);
+  font-size: 1rem;
+}
+
+.plugin-dashboard-view-missing-description {
+  margin: 0;
+  color: var(--text-muted);
+}
+
+@media (max-width: 768px) {
+  .plugin-dashboard-view-missing {
+    margin: var(--space-md);
+    padding: var(--space-md);
+  }
+}