feat: add Homebrew installation support

[chenhg5]

Summary

• Add Homebrew formula for macOS users (homebrew/cc-connect.rb)
• Add GitHub Actions workflow to auto-update formula on release
• Support brew services for background running
• Update README with Homebrew installation instructions

Usage

# Add the tap
brew tap chenhg5/cc-connect

# Install cc-connect
brew install cc-connect

# Start as a background service
brew services start cc-connect

Test plan

• go build ./... passes
• go vet ./... passes
• Manual test: create homebrew tap repo and test formula
• Manual test: brew services start cc-connect works correctly

Notes

To fully enable Homebrew installation, a separate homebrew-cc-connect repository needs to be created as the tap. The GitHub Actions workflow will automatically update the formula when a new release is published.

Closes #413

[chenhg5]

⚠️ CI Lint Failed

The GitHub Actions workflow file has shellcheck issues:

1. SC2086 (multiple locations): Double quote to prevent globbing and word splitting

• Line 18: echo "VERSION=${GITHUB_REF#refs/tags/}" >> $GITHUB_OUTPUT
• Lines 34-43: Multiple variable usages need quoting

2. SC2129 (line 34): Consider using { cmd1; cmd2; } >> file instead of individual redirects

Fix example:

- name: Calculate SHA256 checksums
  id: checksums
  run: |
    VERSION="${{ steps.version.outputs.VERSION }}"
    cd /tmp/assets
    {
      echo "darwin_amd64=$(sha256sum "cc-connect-${VERSION}-darwin-amd64.tar.gz" | cut -d' ' -f1)"
      echo "darwin_arm64=$(sha256sum "cc-connect-${VERSION}-darwin-arm64.tar.gz" | cut -d' ' -f1)"
      echo "linux_amd64=$(sha256sum "cc-connect-${VERSION}-linux-amd64.tar.gz" | cut -d' ' -f1)"
      echo "linux_arm64=$(sha256sum "cc-connect-${VERSION}-linux-arm64.tar.gz" | cut -d' ' -f1)"
    } >> "$GITHUB_OUTPUT"

On the feature itself: Great addition! Homebrew support will make installation much easier for macOS users. The formula structure looks correct with platform-specific downloads and service support.

[chenhg5]

CI lint 失败（shellcheck）：

.github/workflows/homebrew.yml:18:9: SC2086: Double quote to prevent globbing and word splitting
.github/workflows/homebrew.yml:34:9: SC2129: Consider using { cmd1; cmd2; } >> file instead of individual redirects
.github/workflows/homebrew.yml:34:9: SC2086: Double quote to prevent globbing and word splitting (多处)

需要修复 homebrew.yml 中的 shellcheck 问题。（owner PR）