[GH-2867] Translate blog posts to Chinese

[jiayuasu]

Did you read the Contributor Guide?

• Yes, I have read the Contributor Rules and Contributor Development Guide

Is this PR related to a ticket?

• Yes, and the PR name follows the format [GH-XXX] my subject. Closes Add Chinese version of the documentation #2867

What changes were proposed in this PR?

Adds .zh.md Chinese translations for the blog index and all nine existing posts under docs/blog/posts/, extending Chinese documentation coverage to the prose-heavy blog content.

Files added:

• docs/blog/index.zh.md
• docs/blog/posts/h3.zh.md
• docs/blog/posts/intro-sedonadb.zh.md
• docs/blog/posts/intro-sedonadb-0-2.zh.md
• docs/blog/posts/intro-sedonadb-0-3.zh.md
• docs/blog/posts/intro-spatialbench.zh.md
• docs/blog/posts/intro-to-sedona-blog.zh.md
• docs/blog/posts/sedona-2025-year-in-review.zh.md
• docs/blog/posts/spatial-query-benchmarking-databricks.zh.md
• docs/blog/posts/spatial-tables-lakehouse.zh.md

No mkdocs.yml changes are needed — the Blog: 博客 nav translation is already wired from #2920, and the mkdocs-static-i18n plugin picks up the .zh.md files automatically via suffix mode with fallback_to_default: true.

Per-function SQL/Flink/Snowflake reference pages remain English-only, consistent with the decision in #2915 / #2917 / #2918.

How was this patch tested?

• Built the docs locally with uv sync --group docs && uv run mkdocs build and verified the new pages render under /zh/blog/.
• Verified the language switcher round-trips between EN and 中文 on a sample post (e.g. /blog/posts/h3/ ↔ /zh/blog/posts/h3/).
• Confirmed the ASF license header is preserved verbatim at the top of every new .zh.md (pre-commit insert-license hook passes).

Did this PR include necessary documentation updates?

• No, this PR does not affect any public API so no need to change the documentation. (This PR is itself a documentation translation.)