Make release tap update job resilient to missing TAP_PUSH_TOKEN

[Copilot]

The release workflow was failing in the Update Homebrew tap job when TAP_PUSH_TOKEN was not configured, because checkout of HackPoint/homebrew-tap required a token. This change gates tap-update steps on token availability so releases no longer fail on missing optional tap credentials.

• Root-cause handling

  • Added a dedicated token-availability step in update-tap that emits configured=true|false.
  • Logs an explicit skip message when TAP_PUSH_TOKEN is unset.

• Conditional tap update flow

  • Applied if: steps.tap_token.outputs.configured == 'true' to:
    • Checkout homebrew-tap
    • Update formulae with new version + sha256
    • Commit + push tap update
  • Preserves existing behavior when the token is present; safely no-ops when absent.

• Workflow snippet

  - name: Check TAP_PUSH_TOKEN availability
    id: tap_token
    env:
      TAP_PUSH_TOKEN: ${{ secrets.TAP_PUSH_TOKEN }}
    run: |
      if [[ -n "$TAP_PUSH_TOKEN" ]]; then
        echo "configured=true" >> "$GITHUB_OUTPUT"
      else
        echo "configured=false" >> "$GITHUB_OUTPUT"
        echo "TAP_PUSH_TOKEN is not set; skipping Homebrew tap update."
      fi
  
  - name: Checkout homebrew-tap
    if: steps.tap_token.outputs.configured == 'true'
    uses: actions/checkout@v4
    with:
      repository: HackPoint/homebrew-tap
      token: ${{ secrets.TAP_PUSH_TOKEN }}
      path: homebrew-tap