feat(build)!: migrate to Bun and add standalone binary compilation

[gustavovalverde]

BREAKING CHANGES:

• Package is now ESM-only (removed CommonJS builds)
• Development requires Bun 1.2+ instead of pnpm
• Node.js 22+ still supported for runtime consumption

Features:

• Add standalone binary compilation with Bun's --compile flag
  • Support for linux-x64, linux-arm64, darwin-x64, darwin-arm64, windows-x64
  • Baseline and modern CPU variants (Haswell/AVX2+)
  • New GitHub workflow for automated binary builds on releases
  • Binary build script with cross-platform support
• Maintain Node.js compatibility with runtime detection for Bun.CryptoHasher

Build System:

• Replace tsup with Bun.build() for faster builds (~0.6s vs 1.5s)
• Simplify package exports to ESM default only
• Update all 30+ benchmark scripts to use Bun
• Remove pnpm workspace configuration

CI/CD:

• Update all GitHub workflows to use Bun
• Add build-binaries.yml workflow with artifact publishing
• Use SHA-pinned GitHub Actions for security
• Configure proper permissions and credential handling

Development:

• Replace pnpm scripts with Bun equivalents
• Update Husky hooks for Bun compatibility
• Simplify build configuration with fewer dependencies
• Maintain compatibility with Node.js 22+ runtime