refactor(webui): use shared organization explorer tree

webui/scripts/test-organizations-tree-structure.mjs

@@ -0,0 +1,24 @@
+import { readFileSync } from "node:fs";
+
+function assert(condition, message) {
+  if (!condition) throw new Error(message);
+}
+
+const source = readFileSync(
+  new URL("../src/features/organizations/OrganizationsPage.tsx", import.meta.url),
+  "utf8"
+);
+const styles = readFileSync(
+  new URL("../src/styles/organizations.css", import.meta.url),
+  "utf8"
+);
+
+assert(source.includes("ExplorerTree,"), "Organizations imports the central ExplorerTree");
+assert(source.includes("<ExplorerTree"), "the organization hierarchy uses ExplorerTree");
+assert(source.includes("collapsible={false}"), "the always-expanded hierarchy uses the non-collapsible contract");
+assert(source.includes("renderNodeActions="), "per-unit controls use the sibling node-action slot");
+assert(source.includes("<IconButton"), "per-unit controls use the central icon-only action primitive");
+assert(!source.includes("renderUnitTreeNodes"), "the custom recursive renderer was removed");
+assert(!source.includes("organizations-tree-row"), "the custom tree row was removed");
+assert(!source.includes("organizations-tree-node"), "the custom tree node was removed");
+assert(!styles.includes("organizations-tree-"), "Organizations no longer owns shared tree styling");