Add Homebrew tap support with automated formula generation

[mathieubrunpicard]

Summary

This PR adds automated Homebrew formula generation and publishing to the release workflow, enabling users to install pipecorn via brew install pipecorn from the official Homebrew tap.

Key Changes

• Tarball normalization: Added a step to the release workflow that renames oclif-generated tarballs to a consistent format (pipecorn-v<version>-<target>.tar.gz) that Homebrew can reference by version alone
• Homebrew formula template: Updated homebrew/pipecorn.rb.tmpl to support platform-specific URLs and checksums for macOS (arm64/x64) and Linux (arm64/x64) architectures
• Formula rendering script: Created scripts/render-homebrew-formula.sh that generates the final Homebrew formula by:
  • Substituting version placeholders
  • Computing SHA256 checksums for each platform's tarball
  • Validating all placeholders are rendered before output
• Automated tap publishing: Added a new homebrew job to the release workflow that:
  • Downloads release tarballs
  • Renders the formula with correct checksums
  • Pushes the formula to the pipecorn/homebrew-tap repository
• Documentation: Updated README.md to reflect the new Homebrew installation method

Implementation Details

• The formula rendering script validates that all required tarballs exist before proceeding
• Platform detection uses Homebrew's on_macos/on_linux and on_arm/on_intel DSL for architecture-specific installation
• The tap publishing uses a dedicated HOMEBREW_TAP_TOKEN secret for authentication
• The workflow ensures tarballs are published before attempting to render and push the formula via the needs: tarballs dependency

https://claude.ai/code/session_01VJDs7niXGGW2dmPXd1e93S