feat(agent): enrich zpool summary with type, scan state, vdev list

agent/test/fixtures/zfs/zpool_status.json

@@ -26,7 +26,7 @@
       "state": "DEGRADED",
       "scan": {
         "function": "scrub",
-        "state": "FINISHED",
+        "state": "SCANNING",
         "end_time": "Tue Mar 01 08:00:00 2026"
       },
       "error_count": "2",

agent/test/proxmox_agent/collectors/zfs_test.exs

@@ -32,10 +32,19 @@ defmodule ProxmoxAgent.Collectors.ZfsTest do
       assert rpool.size_bytes == 500_000_000_000
       assert rpool.error_count == 0
       assert rpool.degraded_vdev_count == 0
+      assert rpool.pool_type == "mirror"
+      assert rpool.scan_function == "scrub"
+      assert rpool.scan_state == "FINISHED"
+      assert [%{name: "mirror-0", type: "mirror", state: "ONLINE",
+                read_errors: 0, write_errors: 0, checksum_errors: 0}] = rpool.vdevs
 
       assert tank.health == "DEGRADED"
       assert tank.error_count == 2
       assert tank.degraded_vdev_count == 1
+      assert tank.pool_type == "raidz2"
+      assert tank.scan_state == "SCANNING"
+      assert [%{name: "raidz2-0", type: "raidz2", state: "DEGRADED",
+                checksum_errors: 2}] = tank.vdevs
     end
 
     test "populates errors list when zpool fails" do