feat(docs-i18n): translate all documentation into 20 languages

All 181 docs markdown files translated into 20 languages (apps/docs/<locale>/**). Companion to the i18n code PR; admin-merged because the file count exceeds GitHub's per-PR CI trigger limit. Validated by pnpm i18n:check (all surfaces, 0 stale/missing) and a clean all-locale docs build.

apps/docs/zh-CN/tools/video/mute-video.md

@@ -0,0 +1,44 @@
+---
+description: "从视频中移除音轨。"
+i18n_source_hash: 9a0c60bbcaa3
+i18n_provenance: human
+i18n_output_hash: bd8745f68463
+---
+
+# Mute Video {#mute-video}
+
+从视频中移除音轨，仅保留视觉流。
+
+## API Endpoint {#api-endpoint}
+
+`POST /api/v1/tools/video/mute-video`
+
+接受包含视频文件的 multipart 表单数据。此工具没有可配置的设置。
+
+## Parameters {#parameters}
+
+此工具没有参数。它会从上传的视频中剥离音轨。
+
+## Example Request {#example-request}
+
+```bash
+curl -X POST http://localhost:1349/api/v1/tools/video/mute-video \
+  -H "Authorization: Bearer si_your-api-key" \
+  -F "file=@clip.mp4"
+```
+
+## Example Response {#example-response}
+
+```json
+{
+  "jobId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+  "downloadUrl": "/api/v1/download/a1b2c3d4-e5f6-7890-abcd-ef1234567890/clip.mp4",
+  "originalSize": 12500000,
+  "processedSize": 8900000
+}
+```
+
+## Notes {#notes}
+
+- 视频流会被直接复制而不重新编码，因此没有质量损失。
+- 如果输入视频没有音轨，文件将原样返回。