docs: add zh/ja/ru README translations matching the six app languages

Machine-assisted translations of README.md (English authoritative); language switcher
and llms.txt docs list updated in all README variants.

Author: Lukas Geiger

README.es.md

@@ -18,7 +18,7 @@
 [![Última comprobación](https://img.shields.io/badge/last%20checked-2026--10--04-informational.svg)](llms.txt)
 [![llms.txt](https://img.shields.io/badge/llms.txt-available-green.svg)](llms.txt)
 
-[English](README.md) | [Deutsch](README_de.md) | Español
+[English](README.md) | [Deutsch](README_de.md) | Español | [简体中文](README.zh.md) | [日本語](README.ja.md) | [Русский](README.ru.md)
 
 CodeBox es un entorno de desarrollo integrado (IDE) de escritorio local-first para desarrolladores de Windows, Linux y macOS que buscan un editor de código ligero en PySide6 con espacio de trabajo con múltiples pestañas, árbol de proyectos, terminal integrado, indicadores de estado de Git porcelain, resaltado de sintaxis, diagnóstico de Language Server Protocol (LSP) y una arquitectura extensible de complementos de lenguajes en JSON/Python.
 

README.ja.md

@@ -18,7 +18,7 @@
 [![Last Checked](https://img.shields.io/badge/last%20checked-2026--10--04-informational.svg)](llms.txt)
 [![llms.txt](https://img.shields.io/badge/llms.txt-available-green.svg)](llms.txt)
 
-English | [Deutsch](README_de.md) | [Español](README.es.md)
+English | [Deutsch](README_de.md) | [Español](README.es.md) | [简体中文](README.zh.md) | [日本語](README.ja.md) | [Русский](README.ru.md)
 
 CodeBox is a local-first desktop IDE for Windows, Linux, and macOS developers who want a lightweight PySide6 code editor with multi-tab workspace, project tree, integrated terminal, Git status porcelain indicators, syntax highlighting, Language Server Protocol (LSP) diagnostics, and an extensible JSON/Python language plugin architecture.
 

README.md

@@ -18,7 +18,7 @@
 [![Letzte Prüfung](https://img.shields.io/badge/letzte%20pr%C3%BCfung-2026--10--04-informational.svg)](llms.txt)
 [![llms.txt](https://img.shields.io/badge/llms.txt-verf%C3%BCgbar-green.svg)](llms.txt)
 
-[English](README.md) | Deutsch | [Español](README.es.md)
+[English](README.md) | Deutsch | [Español](README.es.md) | [简体中文](README.zh.md) | [日本語](README.ja.md) | [Русский](README.ru.md)
 
 CodeBox ist eine lokale Desktop-IDE für Windows-, Linux- und macOS-Entwickler, die einen leichtgewichtigen PySide6-Codeeditor mit Multi-Tab-Arbeitsbereich, Projektbaum, integriertem Terminal, Git-Porcelain-Statusanzeigen, Syntax-Highlighting, Language-Server-Protocol-Diagnosen (LSP) und einer erweiterbaren deklarativen JSON/Python-Plugin-Architektur suchen.
 

README.ru.md

@@ -11,6 +11,9 @@ Part of the dev-bricks family. Python, MIT.
 - [README.md](https://github.com/dev-bricks/CodeBox/blob/main/README.md): Primary documentation, installation guide, system architecture flowchart, sequence diagram, capabilities table, comparative matrix, and features.
 - [README_de.md](https://github.com/dev-bricks/CodeBox/blob/main/README_de.md): German entry point with localized architecture, workflow diagrams, setup, privacy, and status notes.
 - [README.es.md](https://github.com/dev-bricks/CodeBox/blob/main/README.es.md): Spanish entry point with localized architecture, workflow diagrams, setup, privacy, and status notes.
+- [README.zh.md](https://github.com/dev-bricks/CodeBox/blob/main/README.zh.md): Simplified Chinese entry point (machine-assisted translation; English README is authoritative).
+- [README.ja.md](https://github.com/dev-bricks/CodeBox/blob/main/README.ja.md): Japanese entry point (machine-assisted translation; English README is authoritative).
+- [README.ru.md](https://github.com/dev-bricks/CodeBox/blob/main/README.ru.md): Russian entry point (machine-assisted translation; English README is authoritative).
 - [NOTICE](https://github.com/dev-bricks/CodeBox/blob/main/NOTICE): Copyright attribution and open-bricks umbrella metadata.
 - [THIRD_PARTY_LICENSES.md](https://github.com/dev-bricks/CodeBox/blob/main/THIRD_PARTY_LICENSES.md): Level 1 Software Bill of Materials (SBOM) and governance invariants (`INV-LOCAL-01` to `INV-SLA-10`).
 - [SECURITY.md](https://github.com/dev-bricks/CodeBox/blob/main/SECURITY.md): Bilingual security policy, supported versions, zero-egress invariants, and reporting protocols.