docs(blog): correct rehydrate translation

[Sun-GLiang]

Summary

Correct the literal Chinese translation of rehydrate in the Beyond Function Calling blog:

• use 恢复执行状态（Rehydrate） in Chinese prose;
• use 恢复会话上下文（Rehydrate） in the Chinese diagram;
• keep Rehydrate unchanged in English-only diagrams and leave the English article unchanged.

Fixes #4767

Verification

• git diff --check upstream/main...HEAD
• Confirmed git diff --name-only upstream/main...HEAD contains only docs/blogs/beyond-function-calling.zh-CN.md.
• Automated tests were not run because this is a documentation-only wording change.

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope:

• OpenAI Codex: identified the affected translation contexts, edited two lines, and drafted the Issue and PR text.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No

[Astro-Han]

Approving at 6ab35ed. 「水合」was a literal calque; 「恢复执行状态（Rehydrate）」in prose and 「恢复会话上下文（Rehydrate）」in the diagram read naturally and keep the English term for cross-reference. The two English-only diagrams (lines 393, 454) are correctly left alone, and the file is the only one in docs/ using the old wording. Merges clean.