fix(git): keep machine output raw

[YOMXXX]

Fixes #2487.

Summary

• Keep git commands raw in hook rewrite when stdout is piped, redirected to a file, or explicitly machine-readable (--porcelain, --format, --name-only, -z, etc.).
• Preserve normal model-facing rewrites such as bare git diff and later segments in compound commands.
• Make direct rtk git status --porcelain, rtk git log --format=..., and rtk git diff --name-only pass through byte-for-byte instead of compacting.

Verification

• cargo +1.93.0 test rewrite_git_ -- --nocapture
• cargo +1.93.0 test rewrite_redirect -- --nocapture
• cargo +1.93.0 test registry -- --nocapture
• cargo +1.93.0 test git::git::tests::test_ -- --nocapture
• CLI smoke: rewrite passthrough for git status --porcelain | wc -l, git log --format=%H | sort, git diff --name-only HEAD~1..HEAD; rewrite still active for bare git diff
• CLI smoke: rtk git diff --name-only, rtk git status --porcelain, and rtk git log --format=%H -3 match native git via cmp
• cargo +1.93.0 fmt --all -- --check
• cargo +1.93.0 clippy --all-targets
• cargo +1.93.0 test --all -- --skip small_grep_not_worse_than_plain
• git diff --check