Switch to Astral Python tools: ruff and ty (#7243)

This replaces black, flake8, and mypy with the more modern and efficient
tools `ruff` and `ty` from Astral.

Assisted-by: Antigravity with Gemini

proposals/scripts/check_proposal_names.py

@@ -11,7 +11,6 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 import argparse
 import os
 import pathlib
-
 import re
 import sys
 from typing import List, Optional, Tuple

proposals/scripts/check_proposal_names_test.py

@@ -13,7 +13,6 @@ import pathlib
 import tempfile
 import unittest
 
-
 from proposals.scripts import check_proposal_names