[taigrr]

Summary

• Check staged blob sizes rather than the working tree, preventing unstaged edits/removal from bypassing the size limit or causing false rejections.
• Read NUL-delimited staged paths to preserve spaces, newlines, and glob characters; exclude staged deletions.
• Add regressions for partially staged files, missing working copies, and unusual filenames.

Validation

• All four shell regression suites pass.
• ShellCheck passes for all hooks, installation scripts, and tests.
• git diff --check passes.
• The staged-large/working-small regression fails against the original implementation.