fix: variable handling and command execution in deployment script

[0xwitty]

Explain your changes:
This update resolves issues with variable handling and command execution in the deployment script. Variables are now properly quoted to handle empty values and spaces, single quotes were replaced with double quotes for correct interpolation ($SIGNED, $PACKAGE, $REPO, $CHANNEL), parentheses around wget were removed to prevent a subshell from losing the GPG key, and quotes inside $SCRIPT were escaped to ensure commands execute correctly in docker run.

Explain how you tested your changes:
The deployment script was executed in a controlled environment with various test cases, including empty and spaced variable values. Verified that $SIGNED, $PACKAGE, $REPO, and $CHANNEL are correctly interpolated, GPG keys are preserved, and the echo "deb ..." commands work as expected inside Docker containers.

Checklist:

• Dependency versions are unchanged

  • Notify Velocity team if dependencies must change in CI

• Modified the current draft of release notes with details on what is completed or incomplete within this project

• Document code purpose, how to use it

  • Mention expected invariants, implicit constraints

• Tests were added for the new behavior

  • Document test purpose, significance of failures
  • Test names should reflect their purpose

• All tests pass (CI will check this if you didn't)

• Serialized types are in stable-versioned modules

• Does this close issues? List them

[glyh]

!ci-build-me