[Docs] Fix Chinese engine architecture page rendering - #11164

Purpose

Fix the Chinese engine architecture documentation page rendering issue where normal body content was displayed as raw Markdown/code block content.

Root cause

The Chinese Markdown file had an extra closing code fence immediately after the first Mermaid diagram. That extra ``` opened a new empty fenced code block, causing the following sections to be rendered as code until a later fence closed it.

Changes

• Removed the redundant code fence in docs/zh/architecture/engine/engine-architecture.md.

Verification

• git diff --check
• awk '/^```/{n++} END{print n}' docs/zh/architecture/engine/engine-architecture.md => 16
• JAVA_HOME=/Library/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home ./mvnw spotless:apply
• JAVA_HOME=/Library/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home ./mvnw -q -DskipTests verify