Changing a path's permissions

When to use

• Marking a freshly-written script executable after shell::fs::write.
• Locking down a generated config file ("0600").
• Recursively normalising permissions across a generated tree.

Notes

• mode is an octal string (e.g. "0644", "0755"). uid/gid are optional integers; pass them to also chown.
• updated is the count of paths whose mode or owner the call mutated: 1 for a single-path call, more under recursive: true.
• Symlinks are not followed; chmod operates on the link itself. Recursive walks skip symlink entries so chmod(2)/chown(2) cannot deref to a target outside the walk root.
• uid / gid are advisory: the host backend refuses to chown without sufficient privileges; the call returns the trigger Err rather than silently skipping.
• Same jail and denylist rules as shell::fs::ls.