[core] Consolidate setup scripts into a cross-platform setup.py

script/setup and script/setup.bat implemented the same workflow and were
kept in sync by hand, which had already drifted: the worktree hook fix in
#18843 landed in the bash script only. Both are now thin wrappers around
script/setup.py, so there is one implementation to maintain.

The post-checkout hook also checks for a venv/Scripts layout before doing
anything, so a branch switch on Windows can no longer clear a working
virtual environment.

script/setup

@@ -1,71 +1,7 @@
 #!/usr/bin/env bash
-# Set up ESPHome dev environment
+# Set up ESPHome dev environment.
+#
+# The work is done by setup.py, which script/setup.bat also runs, so the Unix
+# and Windows entry points share one implementation.
 
-set -e
-
-cd "$(dirname "$0")/.."
-if [ -n "$VIRTUAL_ENV" ]; then
-  # A virtual environment is already active (e.g. the devcontainer's pre-provisioned
-  # esphome-venv). Install into it rather than creating a ./venv in the workspace.
-  venv_state=active
-elif [ -x venv/bin/python ]; then
-  # Reuse the environment from an earlier run, so this script can be run again
-  # at any time to pick up dependency changes.
-  venv_state=reused
-  source venv/bin/activate
-else
-  venv_state=created
-  # --clear replaces a partial environment left behind by an interrupted run.
-  if [ -x "$(command -v uv)" ]; then
-    uv venv --clear --seed venv
-  else
-    python3 -m venv --clear venv
-  fi
-  source venv/bin/activate
-fi
-
-if ! [ -x "$(command -v uv)" ]; then
-  python3 -m pip install uv
-fi
-
-uv pip install setuptools wheel
-uv pip install -e ".[dev,test]" --config-settings editable_mode=compat
-
-# A worktree shares one git hooks directory with the main checkout it was
-# created from, so hooks are installed from the main checkout only. Installing
-# from a worktree would point the shared hook at that worktree's virtual
-# environment, breaking it for everyone once the worktree is removed.
-git_dir="$(git rev-parse --absolute-git-dir 2>/dev/null || true)"
-common_dir="$(git rev-parse --path-format=absolute --git-common-dir 2>/dev/null || true)"
-if [ -n "$common_dir" ] && [ "$git_dir" = "$common_dir" ]; then
-  # --overwrite replaces any hook already in place. Without it, prek finds a
-  # previously installed pre-commit hook, moves it aside to
-  # .git/hooks/pre-commit.legacy and keeps calling it, so every commit would
-  # run both tools.
-  prek install --overwrite
-
-  # Prepares the virtual environment for new checkouts and worktrees. Installed
-  # once here, it covers every worktree created from this checkout.
-  if [ -d "$common_dir/hooks" ]; then
-    cp script/git-hooks/post-checkout "$common_dir/hooks/post-checkout"
-    chmod +x "$common_dir/hooks/post-checkout"
-  fi
-fi
-
-mkdir -p .temp
-
-echo
-echo
-case "$venv_state" in
-  created)
-    echo "Virtual environment created at ./venv. Run 'source venv/bin/activate' to use it."
-    ;;
-  reused)
-    echo "Dependencies updated in the existing ./venv. Run 'source venv/bin/activate' to use it."
-    ;;
-  active)
-    echo "Dependencies installed into the active virtual environment:"
-    echo "  $VIRTUAL_ENV"
-    echo "It is already active in this shell, so no 'source venv/bin/activate' is needed."
-    ;;
-esac
+exec python3 "$(dirname "$0")/setup.py" "$@"