Compare manifest directory before passing manifest path

[StantonMatt]

Fixes #202.

The current command builder compares dir.parent() with dir, so a normal working directory always gets --manifest-path appended. This changes the check to compare the current working directory with the selected manifest file's parent directory, which matches the intent from the surrounding code: only pass --manifest-path when the selected package manifest is outside the working directory.

I also split the target/message-format argument appending into a small helper so the same-package and different-package cases are covered directly.

Verification:

• cargo fmt --all -- --check
• cargo test cargo::tests --locked
• cargo test --locked
• cargo clippy -- -D warnings
• git diff --check
• review-fix-loop: no actionable correctness issues found