chore(ui,agent): harden collector parsing, drop dead CSS, resilver label

Addresses final code review:
- to_int/1 now returns 0 on nil or unparseable strings instead of crashing
- remove unused .pool-row CSS (superseded by .pool-block)
- clamp capacity bar width to [0, 100] to prevent visual overflow
- pool_scrub_line/1 uses scan_function so resilver shows as "resilver..."

agent/lib/proxmox_agent/collectors/zfs.ex

@@ -176,7 +176,15 @@ defmodule ProxmoxAgent.Collectors.Zfs do
   end
 
   defp to_int(v) when is_integer(v), do: v
-  defp to_int(v) when is_binary(v), do: String.to_integer(v)
+
+  defp to_int(v) when is_binary(v) do
+    case Integer.parse(v) do
+      {n, _} -> n
+      :error -> 0
+    end
+  end
+
+  defp to_int(_), do: 0
 
   defp max_or_nil([]), do: nil
   defp max_or_nil(list), do: Enum.max(list)