fix(clients): hide WireGuard config after detaching the WG inbound

The client info and QR modals rendered a WireGuard config whenever the
client still carried leftover WG key material (privateKey / publicKey /
allowedIPs / preSharedKey / keepAlive), regardless of whether a WireGuard
inbound was actually attached. After detaching the WG inbound the config
kept showing, built with an empty endpoint port and public key.

Gate wgConfigText on an attached WireGuard inbound (wgInbound) being
present, not just isWireguardClient(client), in both ClientInfoModal and
ClientQrModal.

Also rename the i18n key pages.clients.conf -> config and add the missing
pages.clients keys (wireguardConfig, config, bulkFlow, bulkFlowNoChange,
bulkFlowDisable) to all 12 non-English locales so each one matches en-US.

internal/web/translation/zh-CN.json

@@ -718,6 +718,8 @@
       "tabBasics": "基本",
       "tabCredentials": "凭据",
       "tabLinks": "链接",
+      "wireguardConfig": "WireGuard 配置",
+      "config": "配置",
       "linksHint": "添加第三方分享链接和远程订阅地址，将其包含在该客户端的订阅中。",
       "addExternalLink": "添加外部链接",
       "addExternalSubscription": "添加外部订阅",
@@ -871,6 +873,9 @@
       "bulkAdjustNothing": "应用前请设置天数或流量。",
       "addDays": "添加天数",
       "addTrafficGB": "添加流量 (GB)",
+      "bulkFlow": "设置 flow",
+      "bulkFlowNoChange": "不更改",
+      "bulkFlowDisable": "禁用（清除 flow）",
       "delDepleted": "删除已耗尽",
       "delDepletedConfirmTitle": "删除已耗尽的客户端？",
       "delDepletedConfirmContent": "删除所有流量配额已用尽或已过期的客户端。该操作不可撤销。",