fix: homebrew cask postflight xattr references wrong binary name

[markphelps]

Summary

• Fixes brew install --cask replicate/tap/cog failing with xattr: No such file during postflight
• Extracts inline cask heredoc into a standalone .github/cog.rb.tmpl template file

Problem

The postflight block runs xattr -dr com.apple.quarantine on #{staged_path}/cog, but the downloaded binary is named cog_Darwin_arm64 (or cog_Darwin_x86_64) in the staged directory. The binary stanza creates a symlink with the target name cog in /opt/homebrew/bin/, but does not rename the file in the staged path.

xattr: No such file: /opt/homebrew/Caskroom/cog/0.17.1/cog
Error: Failure while executing; `/usr/bin/env /usr/bin/xattr -dr com.apple.quarantine /opt/homebrew/Caskroom/cog/0.17.1/cog` exited with 1.

Corresponds to replicate/homebrew-tap#32

Fix

Use Hardware::CPU.arm? to construct the correct binary filename in the postflight block, matching the actual file in the staged directory.

Template extraction

The inline heredoc + sed substitution was fragile and hard to read. The cask is now a standalone template at .github/cog.rb.tmpl with envsubst doing variable substitution:

• The .rb.tmpl file looks like the actual Ruby cask -- readable, diffable, syntax-highlightable
• envsubst with an explicit variable list ('${VERSION} ${SHA_ARM} ${SHA_X86}') only substitutes shell placeholders while preserving Ruby #{...} interpolation
• Workflow now does actions/checkout (sparse) to get the template, then downloads checksums

[ask-bonk]

I'm Bonk, and I've done a quick review of your PR.

This PR fixes the Homebrew cask postflight xattr command referencing the wrong binary name, and extracts the inline heredoc into a standalone template file.

One issue with indentation consistency in the template:

cat > /tmp/review.json << 'REVIEW'
{
  "event": "COMMENT",
  "body": "This PR correctly fixes the `xattr` command in the Homebrew cask postflight to reference the actual binary filename (`cog_Darwin_arm64` or `cog_Darwin_x86_64`) instead of the non-existent `cog` in the staged path.\n\nOne minor formatting suggestion for better readability in the template.",
  "comments": [
    {
      "path": ".github/cog.rb.tmpl",
      "start_line": 21,
      "line": 26,
      "side": "RIGHT",
      "body": "The indentation is inconsistent here - the `on_intel` block content is at a different level than `on_arm`. For better readability and to match standard Ruby formatting:\n\n```suggestion\n  binary \"cog_Darwin_#{on_intel do\n                         \\\"x86_64\\\"\n                       end\n                       on_arm do\n                         \\\"arm64\\\"\n                       end}\", target: \"cog\"\n```\n\nAlternatively, consider using a more compact form:\n```ruby\n  binary \"cog_Darwin_#{Hardware::CPU.arm? ? \\\"arm64\\\" : \\\"x86_64\\\"}\", target: \"cog\"\n```\n\nThis would be consistent with how the `postflight` block handles the architecture detection."
    }
  ]
}
REVIEW
gh api repos/replicate/cog/pulls/2899/reviews --input /tmp/review.json

github run