Craft: split unrelated work into separate PRs off master (except when depending on unmerged work)

When a feature or fix is logically independent from existing work on the current branch, don't append it to that branch. Create a new branch off master (git fetch origin master && git checkout -b <branch> origin/master), stash changes, pop on the new branch, commit, push with -u, open PR. This keeps PRs self-contained, independently reviewable, and revertable. Applies even when the current branch name thematically overlaps (e.g., a branch named fix/dependabot-security-alerts is not the right home for a feature adding security: prefix recognition). Exception: if the new work genuinely DEPENDS on code only present in an unmerged sibling PR (e.g. PR C's publish-state threading needs PR B's workspace resolver), branch off that sibling's branch instead of master, and plan to rebase onto master once the sibling merges. Hold the dependent PR's review/opening until the sibling settles, to avoid reviewing against a moving base.