Rebase onto base branch

Rebase the current feature branch onto the latest base branch to keep it up-to-date and prevent merge conflicts from accumulating.

Step 1: Validate preconditions

Run these checks in order. If any fail, inform the user and stop.

Detect current branch and base branch

git rev-parse --abbrev-ref HEAD

If the result is main, master, or develop — inform the user they're already on the base branch and stop.

Detect the base branch: