feat: add Homebrew formula and Scoop manifest with automated release workflow

[NanamiMio]

Summary

This PR adds native package manager support for Homebrew (macOS / Linux) and Scoop (Windows), along with automated manifest updates in the GitHub Actions release workflow.

1. Homebrew Formula (Formula/ptd-cli.rb)

• Pre-compiled binary distribution for 4 target architectures:
  • macOS: aarch64-apple-darwin (Apple Silicon), x86_64-apple-darwin (Intel)
  • Linux: aarch64-unknown-linux-gnu (ARM64), x86_64-unknown-linux-gnu (x86_64)
• Zero build dependencies (rust/llvm not required), instant installation in < 1s.
• Installs both ptd and ptd-host.
• Written using an idiomatic SHA256S Map structure.

2. Scoop Manifest (bucket/ptd-cli.json)

• Direct binary zip distribution for Windows x86_64-pc-windows-msvc.
• Includes autoupdate and checkver configuration.

3. Automated Release Workflow (.github/workflows/release.yml)

• Automatically computes SHA256 checksums for all 5 release artifacts upon release / tag push.
• In-place updates Formula/ptd-cli.rb and bucket/ptd-cli.json with the new version and SHA256 hashes.
• Commits and pushes both manifest updates in a single atomic commit [skip ci].
• Keeps source files as the single source of truth without duplicating templates.

4. Documentation

• Updated README.md and README.en.md with installation commands:

  # Homebrew
  brew tap pt-plugins/ptd-cli https://github.com/pt-plugins/ptd-cli
  brew install ptd-cli
  
  # Scoop
  scoop bucket add ptd-cli https://github.com/pt-plugins/ptd-cli
  scoop install ptd-cli

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概述（中文）

本 PR 为 ptd-cli 增加了 Homebrew (macOS/Linux) 和 Scoop (Windows) 包管理器支持，并集成了 Release CI 自动更新机制：

1. Homebrew Formula (Formula/ptd-cli.rb)：支持 macOS 及 Linux 的 ARM64 与 x86_64 预编译二进制分发，0 构建依赖，秒级安装。
2. Scoop Manifest (bucket/ptd-cli.json)：支持 Windows 64位预编译 Zip 安装与自动更新检测。
3. Release CI 自动化 (.github/workflows/release.yml)：发版时自动计算各平台 SHA256，原地更新 Formula 与 Scoop Manifest，并在单次原子 Commit 内推回主分支。
4. 文档更新：更新中英文 README 中的安装指南。