Relocate the Kitty scrollback watcher out of the single-purpose kitty/
directory into scripts/kitty-fish-config-watcher.py, and change the
installer to symlink it into the Kitty config directory instead of
copying it.
The symlink always tracks the canonical source, which removes the
version-staleness comparison and the copy-vs-refresh messaging. uninstall
now removes a symlink (including a dangling one) or a legacy copied file.
Existing installs migrate automatically on the next `kitty-logging install`.
Docs (README, docs/fish-config.md, wiki) updated to match.