Add bleach to the base-workspace manifest

[codeforester]

Problem

basectl workspace status reports bleach as a warning because the repository is discovered under the workspace root but is not listed in base-workspace/workspace.yaml.

The repository is a healthy Base-managed peer repository, so the manifest should include it as an optional workspace member. The repository currently uses the legacy master default branch, while this workspace manifest intentionally rejects master branch metadata.

Acceptance criteria

• Add bleach to workspace.yaml with its canonical HTTPS remote.
• Keep it optional so missing bleach does not make the workspace update or clone fail.
• Omit the optional default_branch metadata until the repository migrates from master to the workspace-standard main branch.
• Confirm basectl workspace check no longer reports BASE-W011 for bleach.
• Confirm basectl workspace status reports bleach as an expected optional repository.