feat: VLAN-aware bridges via New-PveNetwork and Set-PveNetwork

PveNetwork already deserialised bridge_vlan_aware as BridgeVlanAware, so a
VLAN-aware bridge could be read back but never created or changed. Both write
paths now take a -BridgeVlanAware switch.

Clearing the flag does not use bridge_vlan_aware=0. PVE merges the supplied
keys onto the stored stanza and accepts that 0 without acting on it, so the
obvious form is a silent no-op: an integration run against PVE 9 issued it and
Get-PveNetwork still reported 1. The endpoint's delete list is what actually
removes the key. The API schema advertises a plain boolean and gives no hint of
this, which is why the behaviour is pinned by an integration test rather than
inferred.

Set-PveNetwork guards the switch on BoundParameters so an update that omits it
leaves the flag alone; the create path follows the existing -Autostart form.
Only bridge_vlan_aware is added. bridge_vids is an independent parameter that
PVE defaults to 2-4094, and the issue asks only for the flag.

Coverage: the integration suite pins create, disable, re-enable, and that an
unrelated Set leaves the flag alone -- that last one kills a mutant that drops
the BoundParameters guard, which every other test survives. A model test pins
the read path the assertions depend on. The Pester unit tests assert only
parameter metadata; the defect is server-side, so nothing offline can catch it.

Closes #92

tests/PSProxmoxVE.Core.Tests/Models/NetworkModelTests.cs

@@ -109,5 +109,17 @@ namespace PSProxmoxVE.Core.Tests.Models
             Assert.Equal("vmbr1", networks[1].Iface);
             Assert.Equal("10.0.0.1/24", networks[1].Cidr);
         }
+
+        [Fact]
+        public void PveNetwork_Deserialize_Pve9_BridgeVlanAware_MapsAndIsNullWhenAbsent()
+        {
+            var json = TestHelper.LoadFixture("pve9_networks.json");
+            var data = JObject.Parse(json)["data"];
+            Assert.NotNull(data);
+            var networks = data.ToObject<PveNetwork[]>();
+            Assert.NotNull(networks);
+            Assert.Equal(1, networks[1].BridgeVlanAware);
+            Assert.Null(networks[0].BridgeVlanAware);
+        }
     }
 }