[GH-2867] Translate SQL API Geometry / Geography functions to Chinese (Phase 8)

[jiayuasu]

Part of #2867.

Scope

Translate the SQL API Geometry and Geography function reference pages (~70 files).

Files

• `docs/api/sql/Geometry-Functions.md` (single large reference page; if it exists as one file, translate sections incrementally)
• `docs/api/sql/geography/Geography-Functions.md`
• `docs/api/sql/geography/Geography-Constructors/*.md`
• `docs/api/sql/geography/Geography-Functions/*.md`
• `docs/api/sql/Spatial-Statistics/*.md`

Deliverable

A `*.zh.md` sibling for each English page. Function signatures, parameter names, code samples, and SQL output stay in English; descriptive prose, parameter descriptions, and `Description` / `Format` / `Example` headings are translated.

Notes

• Many of these pages share a common structure (Description / Format / Parameters / Example / Output). Establish the translation conventions for these section headings in this PR so subsequent function-reference PRs (Phases 9-11) follow the same pattern.