feat: add linux riscv64 package support

[xiwangly2]

Summary

• Add a linux-riscv64 package target and release artifact wiring.
• Treat riscv64 as a degraded portable package that uses system Node.js and system unzip/zip/7z tools instead of unavailable bundled native assets.
• Document the support boundary and update contributor guidance so new architectures do not overstate unsupported PTY, ZipTools, 7z, SteamCMD, or game-server assets.

Validation

• npm run package:linux:riscv64:no-zip
• cd server && npm test -- --runTestsByPath src/__tests__/7z-extract-compress.test.ts src/__tests__/7z-binary-name.test.ts src/__tests__/7z-property.test.ts
• RevyOS / Lichee Pi 4A (10.31.0.225, riscv64): installed distro Node.js 20.18.0 plus zip/7z tools, started the generated linux-riscv64 package on port 39031, and verified the web UI returned HTML over HTTP. Logs showed expected PTY degradation and system ZIP/7z fallback.

Notes

Docker is intentionally left at amd64/arm64 because the current Dockerfile still depends on architecture-specific SteamCMD, Java, PTY, ZipTools, and 7z assumptions that are not ready for riscv64.

[xiwangly2]

追加了一轮 Java/包管理器架构边界修正：

• 后端 Java 下载产物判断抽到 javaDownloadArtifacts，riscv64、macOS 和未知 Linux 架构不再回退到 Linux x64 JDK。
• 前端 Java 卡片按真实平台/架构禁用下载式安装，并提示改用系统 OpenJDK。
• Linux 包管理器在非 x86 架构隐藏 :i386 包，避免 riscv64/arm64 打开包列表时尝试启用错误架构；同时加入 OpenJDK headless 包候选。

验证：

• cd server; npm test -- --runTestsByPath src/__tests__/java-download-artifacts.test.ts src/__tests__/7z-extract-compress.test.ts src/__tests__/7z-binary-name.test.ts src/__tests__/7z-property.test.ts：4 suites / 33 tests passed。
• npm run package:linux:riscv64:no-zip：通过，仍按预期跳过内置 Node.js、PTY、Zip-Tools 和 7z。
• RevyOS Lichee Pi 4A (10.31.0.225, riscv64)：打包产物导入 javaDownloadArtifacts 后 linux/riscv64 返回 UnsupportedJavaDownloadError；APT 包列表 APT_I386_VISIBLE 0，可见 default-jre-headless,openjdk-11-jre-headless,openjdk-17-jre-headless,openjdk-21-jre-headless；启动打包面板后 HTTP_OK，日志显示预期的 PTY 不支持和系统 /usr/bin/7z 降级。

[xiwangly2]

追加更新：已继续收敛 x64-only 游戏部署路径，当前 Draft PR 分支更新到 a6978ae。

本次新增：

• 后端新增统一架构守卫，SteamCMD 相关安装、分支查询、更新入口在非 x64 平台会提前返回明确的 400 错误。
• Factorio headless 自动部署也加了平台/架构保护，只允许 Linux x86_64；非 x86_64 建议走手动文件部署。
• 前端从原来的 ARM-only 判断泛化为 non-x64 limited architecture，riscv64/arm64 等特殊架构会隐藏 SteamCMD/市场/在线部署等不适用入口，并在安装向导中跳过 SteamCMD 在线安装。
• docs/多架构支持说明.md 补充 SteamCMD 和 Factorio 的限制说明。

验证：

• git diff --check
• cd server; npm test -- --runTestsByPath src/__tests__/architecture-support.test.ts src/__tests__/java-download-artifacts.test.ts src/__tests__/7z-extract-compress.test.ts src/__tests__/7z-binary-name.test.ts src/__tests__/7z-property.test.ts
• cd server; npm run build
• cd client; npm run build
• npm run package:linux:riscv64:no-zip
• RevyOS Lichee Pi 4A / riscv64 (10.31.0.225) 解包运行验证：服务 HTTP OK，SteamCMD/Factorio 守卫均返回 UnsupportedArchitectureError，7z 走系统 /usr/bin/7z 降级，PTY 不可用仍为预期降级行为。