fix(git): preserve explicit branch listings

[YOMXXX]

Summary

• preserve native git output for explicit rtk git branch -a/--all and -r/--remotes
• keep the existing compact branch summary for default rtk git branch
• add integration coverage with a local remote repo for branch -a and -r

Fixes #2137

Verification

• cargo +1.93.0 fmt --check
• git diff --check
• cargo +1.93.0 test --test git_branch_test -- --nocapture
• cargo +1.93.0 test filter_branch -- --nocapture
• cargo +1.93.0 clippy --all-targets
• cargo +1.93.0 test --all -- --skip small_grep_not_worse_than_plain