Remove uv-tools.sh and the global uv tools

Remove uv-tools.sh and the global uv tools Deletes the last non-Nix tool script. grip, llvd, radon, semble, hypothesis, spec-kitty-cli and weasyprint are no longer wanted, so nothing is left for it to install. uv itself stays in the Nix package set, and two project mise.toml files still pin it - this only removes the globally installed uv tools, not uv. Drops the uv-tools target from the Makefile, the step from bootstrap.sh's closing instructions, and the references from the README. The repo is now 12 files, and every global tool on the machine comes from Nix. The installed uv tools are not removed by this commit; clear them with `uv tool uninstall`.