docs(settings): clarify Sub Port/Sub Domain double as subscription-link fallback (#5721)

* docs(settings): clarify Sub Port/Sub Domain double as subscription-link fallback

subPort/subDomain are documented purely as the subscription service's own
listen address, but when "Reverse Proxy URI" is empty, GetDefaultSettings
silently reuses them (with the admin API request's own Host header as the
domain fallback) to build the subscription link/QR shown in the panel.
Behind a reverse proxy where the sub service listens on an internal port
and is exposed externally on a different port/domain, this produces a
broken link even though "Reverse Proxy URI" already solves it - nothing
in the UI text pointed to it. Clarify all locales.

* docs(settings): fix wording nits from review (punctuation, CJK parens, es-ES field name)

- en-US/id-ID/pt-BR/tr-TR/uk-UA/ar-EG: add terminating punctuation before
  the appended sentence so it doesn't run on directly after the closing
  parenthesis.
- zh-CN/zh-TW/ja-JP: restore full-width CJK parentheses around the
  pre-existing parenthetical, matching the rest of each file.
- es-ES: subURIDesc referenced "Dominio/Puerto de escucha", but the
  actual field labels in this locale are "Dominio de Escucha" and
  "Puerto de Suscripción".

---------

Co-authored-by: Volov <volovdata@google.com>

internal/web/translation/zh-CN.json

@@ -1206,7 +1206,7 @@
       "subListen": "监听 IP",
       "subListenDesc": "订阅服务监听的 IP 地址（留空表示监听所有 IP）",
       "subPort": "监听端口",
-      "subPortDesc": "订阅服务监听的端口号（必须是未使用的端口）",
+      "subPortDesc": "订阅服务监听的端口号（必须是未使用的端口）。当下方「反向代理 URI」为空时，也会用来生成面板中显示的订阅链接/二维码——如果订阅是通过反向代理的其他端口访问的，请改为设置「反向代理 URI」。",
       "subCertPath": "公钥路径",
       "subCertPathDesc": "订阅服务使用的公钥文件路径（以 '/' 开头）",
       "subKeyPath": "私钥路径",
@@ -1214,13 +1214,13 @@
       "subPath": "URI 路径",
       "subPathDesc": "订阅服务使用的 URI 路径（以 '/' 开头，以 '/' 结尾）",
       "subDomain": "监听域名",
-      "subDomainDesc": "订阅服务监听的域名（留空表示监听所有域名和 IP）",
+      "subDomainDesc": "订阅服务监听的域名（留空表示监听所有域名和 IP）。当「反向代理 URI」为空时，也会作为显示的订阅链接的回退域名——如果面板和订阅通过不同的域名访问(例如位于反向代理之后)，请设置「反向代理 URI」。",
       "subUpdates": "更新间隔",
       "subUpdatesDesc": "客户端应用中订阅 URL 的更新间隔（单位：小时）",
       "subEncrypt": "编码",
       "subEncryptDesc": "订阅服务返回的内容将采用 Base64 编码",
       "subURI": "反向代理 URI",
-      "subURIDesc": "用于代理后面的订阅 URL 的 URI 路径",
+      "subURIDesc": "用于订阅链接和二维码的完整基础 URL(scheme://域名[:端口]/路径/)，会替代监听域名/监听端口使用。当订阅通过反向代理访问，或使用与上面不同的域名/端口访问时，请设置此项。",
       "externalTrafficInformEnable": "外部交通通知",
       "externalTrafficInformEnableDesc": "每次流量更新时通知外部 API。",
       "externalTrafficInformURI": "外部流量通知 URI",