chore: remove dead cookiecutter regeneration infrastructure

The repo was bootstrapped from `cookiecutter-pylibrary`. The
regeneration scaffolding has been sitting around since then — unused,
out of date, and in some cases pointing at infrastructure (AppVeyor)
that hasn't been part of CI for years. Knock it all down in one
sweep so there's nothing dead-by-design in the tree after this PR.

Removed
- `.cookiecutterrc` — cookiecutter regen metadata.
- `ci/bootstrap.py` — entry point for regenerating workflow files
  from the templates.
- `ci/templates/` (whole directory):
  - `.appveyor.yml` template (AppVeyor isn't wired up).
  - `.github/workflows/github-actions.yml` Jinja template (the live
    workflow has evolved past it via #32, #35, #37).

Coupled updates
- `tox.ini`: dropped the `[testenv:bootstrap]` env (calls deleted
  `bootstrap.py`) and the `bootstrap` reference in the basepython
  selector.
- `MANIFEST.in`: removed `include .cookiecutterrc`.
- `setup.cfg`: removed `ci/templates` from the flake8 `exclude` and
  isort `skip` lists (dead exclusion paths).
- `.pre-commit-config.yaml`: removed `ci/templates` from the
  top-level `exclude` regex.
- `tests.local.sh`: replaced the per-version `if/elif` chain (which
  still listed Python 3.7 and missed 3.12-3.14) with a single
  programmatic `tox -e py$VERSION` lookup against
  `tox --listenvs-all`. Self-maintaining when the matrix changes.
- `CHANGELOG.rst`: added a Housekeeping bullet for this PR.

Live and untouched
- `ci/requirements.txt` is still installed by every CI workflow
  (`pip install -r ci/requirements.txt`). Not regen-related.

Closes #46

1 files changed, 0 insertions, 93 deletions

diff --git a/ci/bootstrap.py b/ci/bootstrap.py
deleted file mode 100755
index 3ca06b7..0000000
--- a/ci/bootstrap.py
+++ /dev/null
@@ -1,93 +0,0 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-from __future__ import absolute_import
-from __future__ import print_function
-from __future__ import unicode_literals
-
-import os
-import subprocess
-import sys
-from os.path import abspath
-from os.path import dirname
-from os.path import exists
-from os.path import join
-from os.path import relpath
-
-base_path = dirname(dirname(abspath(__file__)))
-templates_path = join(base_path, "ci", "templates")
-
-
-def check_call(args):
-    print("+", *args)
-    subprocess.check_call(args)
-
-
-def exec_in_env():
-    env_path = join(base_path, ".tox", "bootstrap")
-    if sys.platform == "win32":
-        bin_path = join(env_path, "Scripts")
-    else:
-        bin_path = join(env_path, "bin")
-    if not exists(env_path):
-        import subprocess
-
-        print("Making bootstrap env in: {0} ...".format(env_path))
-        try:
-            check_call([sys.executable, "-m", "venv", env_path])
-        except subprocess.CalledProcessError:
-            try:
-                check_call([sys.executable, "-m", "virtualenv", env_path])
-            except subprocess.CalledProcessError:
-                check_call(["virtualenv", env_path])
-        print("Installing `jinja2` into bootstrap environment...")
-        check_call([join(bin_path, "pip"), "install", "jinja2", "tox"])
-    python_executable = join(bin_path, "python")
-    if not os.path.exists(python_executable):
-        python_executable += '.exe'
-
-    print("Re-executing with: {0}".format(python_executable))
-    print("+ exec", python_executable, __file__, "--no-env")
-    os.execv(python_executable, [python_executable, __file__, "--no-env"])
-
-
-def main():
-    import jinja2
-
-    print("Project path: {0}".format(base_path))
-
-    jinja = jinja2.Environment(
-        loader=jinja2.FileSystemLoader(templates_path),
-        trim_blocks=True,
-        lstrip_blocks=True,
-        keep_trailing_newline=True,
-    )
-
-    tox_environments = [
-        line.strip()
-        # 'tox' need not be installed globally, but must be importable
-        # by the Python that is running this script.
-        # This uses sys.executable the same way that the call in
-        # cookiecutter-pylibrary/hooks/post_gen_project.py
-        # invokes this bootstrap.py itself.
-        for line in subprocess.check_output([sys.executable, '-m', 'tox', '--listenvs'], universal_newlines=True).splitlines()
-    ]
-    tox_environments = [line for line in tox_environments if line.startswith('py')]
-
-    for root, _, files in os.walk(templates_path):
-        for name in files:
-            relative = relpath(root, templates_path)
-            with open(join(base_path, relative, name), "w") as fh:
-                fh.write(jinja.get_template(join(relative, name)).render(tox_environments=tox_environments))
-            print("Wrote {}".format(name))
-    print("DONE.")
-
-
-if __name__ == "__main__":
-    args = sys.argv[1:]
-    if args == ["--no-env"]:
-        main()
-    elif not args:
-        exec_in_env()
-    else:
-        print("Unexpected arguments {0}".format(args), file=sys.stderr)
-        sys.exit(1)