fix(bbup): accept v-prefixed versions

[loglapa]

Closes #17107.

Summary

Allow bbup -v to accept release versions with or without a leading v. bbup owns release-tag construction and now strips one optional user-supplied prefix before version comparison and URL generation, preventing tags such as vv0.77.1.

Add the prefixed form to the existing real-install test matrix and normalize its expected bb --version value. Existing unprefixed and shell-config behavior remains covered.

Testing

Run in the repository aztecprotocol/build:3.0 ARM64 container:

• barretenberg/bbup/run_test.sh install v0.77.1
• barretenberg/bbup/run_test.sh install 0.77.1
• barretenberg/bbup/run_test.sh shell_config 0.77.1

Additional checks:

• bash -n on all three changed scripts
• official ShellCheck container with --severity=error (the files retain pre-existing lower-severity findings)