feat(wireguard): client config UX, collapsible config card, configurable DNS

Land the WireGuard client-config UX work on main (the upstream PR #5642
branch could not be pushed to).

- Reusable collapsible ConfigBlock (copy/download/QR, actions aligned right)
  for the client .conf, used by client info and the public sub page.
- Correct .conf: canonical PresharedKey casing and DNS sourced from the inbound
  (configurable per-inbound, default 1.1.1.1, 1.0.0.1).
- Configurable per-inbound DNS for WireGuard (schema + form + backend hint via
  InboundOption.WgDns); inert at the Xray layer.
- Public sub page now shows the WireGuard config, rebuilt from the share link;
  the Go wireguard:// link carries dns/presharedkey/keepalive for completeness.
- QR enabled for the wireguard:// link; link rows are compact like other protocols.
- Client information order is subscription, copy URL, WireGuard config; the
  redundant config tab is removed from the add/edit client modal.
- Drop the Inbound Information and QR Code row actions for WireGuard inbounds.

frontend/public/openapi.json

@@ -1854,6 +1854,15 @@
           "tlsFlowCapable": {
             "example": true,
             "type": "boolean"
+          },
+          "wgDns": {
+            "type": "string"
+          },
+          "wgMtu": {
+            "type": "integer"
+          },
+          "wgPublicKey": {
+            "type": "string"
           }
         },
         "required": [
@@ -2751,7 +2760,10 @@
                       "remark": "VLESS-443",
                       "ssMethod": "",
                       "tag": "in-443-tcp",
-                      "tlsFlowCapable": true
+                      "tlsFlowCapable": true,
+                      "wgDns": "",
+                      "wgMtu": 0,
+                      "wgPublicKey": ""
                     }
                   ]
                 }