Git hygiene

Description

Advise on and review Git practices — atomic commits and clear messages (Conventional Commits), branch naming and short-lived branches, pull request size and descriptions, separating formatting/refactor commits (.git-blame-ignore-revs), rebasing vs merging, safe force-pushing, .gitignore and .gitattributes (line endings on Windows), keeping secrets out of history and responding when one leaks, tags and releases, and recovering from mistakes (reflog, revert vs reset). Use whenever the user asks to commit, write a commit message or PR description, clean up a branch, undo a git mistake, set up a repo, sees CRLF/LF churn, or accidentally committed a secret.