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- remove unused .pool-row CSS (superseded by .pool-block)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/test/proxmox_agent/collectors/zfs_test.exs

@@ -104,6 +104,43 @@ defmodule ProxmoxAgent.Collectors.ZfsTest do
       # log vdev is retained in the per-pool vdevs list even though it's ignored for layout classification
       assert Enum.any?(by_name["mirror_with_log"].vdevs, &(&1.type == "log"))
     end
+
+    test "tolerates nil and non-integer error counters" do
+      list_json =
+        Jason.encode!(%{
+          "pools" => %{
+            "weird" => %{"name" => "weird", "size" => 1, "alloc" => 0, "free" => 1,
+                        "frag" => 0, "cap" => 0, "health" => "ONLINE"}
+          }
+        })
+
+      status_json =
+        Jason.encode!(%{
+          "pools" => %{
+            "weird" => %{
+              "name" => "weird", "state" => "ONLINE", "error_count" => nil,
+              "vdevs" => %{
+                "disk-0" => %{"name" => "disk-0", "vdev_type" => "disk", "state" => "ONLINE",
+                              "read_errors" => nil, "write_errors" => "abc",
+                              "checksum_errors" => "0"}
+              }
+            }
+          }
+        })
+
+      runner = fn
+        "zpool", ["list" | _] -> {:ok, list_json}
+        "zpool", ["status" | _] -> {:ok, status_json}
+      end
+
+      sample = Zfs.collect_pools(runner: runner)
+      [pool] = sample.pools
+      assert pool.error_count == 0
+      [vdev] = pool.vdevs
+      assert vdev.read_errors == 0
+      assert vdev.write_errors == 0
+      assert vdev.checksum_errors == 0
+    end
   end
 
   describe "collect_datasets/1" do