Allow beta release base override

[sidmohan0]

Summary

This updates the release workflow so manual alpha/beta dispatches can use version_override as the stable prerelease base.

Why:

• The current dev version is 4.3.0b11.
• Dispatching a beta without this change would produce 4.3.0b12.
• For the v4.4 bridge beta, we want to dispatch release_type=beta with version_override=4.4.0, producing 4.4.0b1.

Validation

ruby -e 'require "yaml"; YAML.load_file(".github/workflows/release.yml"); puts "release workflow YAML ok"'
BASE=4.4.0; BETA_NUM=1; while git tag -l "vb" | grep -q .; do BETA_NUM=1; done; echo "b"
git diff --check

Expected beta version simulation returned 4.4.0b1.

Next step after merge

Run the Release workflow manually with:

• release_type=beta
• version_override=4.4.0
• dry_run=true first
• then rerun with dry_run=false if the dry run looks good.