Add VLAN overview table to VLAN configuration page

Below the configuration form, a new table lists all configured VLANs
with their port memberships: Member, Tagged, Untagged, and PVID
columns. Port ranges are formatted compactly (e.g. "1-2,5").

Port-to-bit mapping uses the existing physToLogPort[] array populated
by /status.json, so the table is consistent with the icon view in
fetchVLAN() and works on any supported machine.

Each row has a delete button that sends "vlan N d" via /cmd, with
a confirmation dialog. VLAN 1 cannot be deleted (no button shown).

Table and dropdown both refresh automatically after Update/Create
and after delete via a new refreshVlanViews() helper.

The N+1 request pattern (1x /vlanlist + Nx /vlan.json) keeps the
backend simple and avoids buffer overflow risks for systems with
many VLANs. For typical configurations (<50 VLANs), page load
remains under one second.

html/vlan_sub.js

@@ -28,7 +28,7 @@ async function vlanSub() {
       });
       console.log('Completed!', response);
     }
-    loadVlanList();
+    refreshVlanViews();
   } catch(err) {
     console.error(`Error: ${err}`);
   }