fix(widget): translate zh_CN availability keys (#14288)

Translate missing Simplified Chinese live-chat widget availability and
reply-time strings so visitors using `zh_CN` no longer see English
fallbacks in offline and pre-chat states.

## Closes

N/A

## How to test

- Open the widget with `Widget Locale = 中文 (zh_CN)` and set the team
offline. The availability card should stay in Chinese.
- Configure working hours so the widget shows minute, hour, tomorrow,
and day-specific return states. The `{time}`, `{n}`, and `{day}`
placeholders should render correctly.

## What changed

- Translated missing `THUMBNAIL.AUTHOR.NOT_AVAILABLE`,
`TEAM_AVAILABILITY.BACK_AS_SOON_AS_POSSIBLE`, and `REPLY_TIME.*` strings
in `app/javascript/widget/i18n/locale/zh_CN.json`.
- Kept the scope limited to Simplified Chinese.

Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/javascript/widget/i18n/locale/zh_CN.json

@@ -14,24 +14,24 @@
   },
   "THUMBNAIL": {
     "AUTHOR": {
-      "NOT_AVAILABLE": "Not available"
+      "NOT_AVAILABLE": "暂无"
     }
   },
   "TEAM_AVAILABILITY": {
     "ONLINE": "在线",
     "OFFLINE": "当前已离线",
-    "BACK_AS_SOON_AS_POSSIBLE": "We will be back as soon as possible"
+    "BACK_AS_SOON_AS_POSSIBLE": "我们会尽快回复您"
   },
   "REPLY_TIME": {
     "IN_A_FEW_MINUTES": "通常在几分钟内回复您",
     "IN_A_FEW_HOURS": "通常在几小时内回复您",
     "IN_A_DAY": "通常在一天之内回复您",
-    "BACK_IN_HOURS": "We will be back online in {n} hour | We will be back online in {n} hours",
-    "BACK_IN_MINUTES": "We will be back online in {time} minutes",
-    "BACK_AT_TIME": "We will be back online at {time}",
-    "BACK_ON_DAY": "We will be back online on {day}",
-    "BACK_TOMORROW": "We will be back online tomorrow",
-    "BACK_IN_SOME_TIME": "We will be back online in some time"
+    "BACK_IN_HOURS": "{n} 小时后恢复在线",
+    "BACK_IN_MINUTES": "{time} 分钟后恢复在线",
+    "BACK_AT_TIME": "{time} 恢复在线",
+    "BACK_ON_DAY": "{day} 恢复在线",
+    "BACK_TOMORROW": "明天恢复在线",
+    "BACK_IN_SOME_TIME": "稍后恢复在线"
   },
   "DAY_NAMES": {
     "SUNDAY": "周日",