feat: compare limit 9, format-aware import placeholder, help links

- Raise compare limit from 8 to 9 (server + client, toast on overflow)
- Make import textarea placeholder match selected format (CSV/JSON/YAML/auto)
- Add GuideHelp links to admin create/edit user dialogs and tool import dialog

artifacts/api-server/src/routes/tools.ts

@@ -268,8 +268,8 @@ router.get("/compare", requireFeature("compare"), async (req, res): Promise<void
     res.status(400).json({ error: "Provide at least one ids value, e.g. ?ids=1,2,3" });
     return;
   }
-  if (ids.length > 8) {
-    res.status(400).json({ error: "Maximum of 8 tools can be compared" });
+  if (ids.length > 9) {
+    res.status(400).json({ error: "Maximum of 9 tools can be compared" });
     return;
   }
   const tools = await db.select().from(toolsTable).where(and(isNull(toolsTable.deletedAt), inArray(toolsTable.id, ids)));