Function get_local_git_dir 

pub fn get_local_git_dir(cwd: &Path) -> Option<String>

Get the absolute path to the .git directory for a working directory.

Uses direct file system access for speed (~15µs vs ~640µs with libgit2). Walks up the directory tree to find .git, handling both normal repos and worktrees.

Returns None if:

• The directory is not a git repository
• Any error occurs

Example

use std::path::Path;
use mi6_core::context::get_local_git_dir;

// In a normal repo: returns "/path/to/repo/.git"
let git_dir = get_local_git_dir(Path::new("/path/to/repo"));

// In a worktree: returns "/path/to/main/.git/worktrees/branch-name"
let git_dir = get_local_git_dir(Path::new("/path/to/worktree"));