Handle quoted Git paths in allowed dirty-path checks #201

Problem

git_only_path_dirty parses git status --porcelain by taking everything after the first three characters. Git quotes paths containing spaces and other special characters, so a tracked change such as shared/hello world.txt is compared as a quoted Git representation instead of the caller's literal path.

As a result, git_update_repo can incorrectly skip an update even when all dirty files are inside the allowed path.

Scope

Replace the line-oriented status parsing with a Git-supported machine-readable format and compare decoded paths. Preserve correct handling for ordinary paths, rename/copy records, submodules, and changes in both the index and worktree.

Acceptance criteria

• Allowed dirty paths containing spaces are recognized.
• Quoted and special-character paths are compared literally.
• Rename/copy records validate every relevant path.
• Add focused BATS coverage for at least a path containing spaces and a rename.
• Keep the existing refusal behavior for changes outside the allowed path.