Support path-like filenames in edit

[arturict]

What changed

• accept a single os.PathLike[str] or an iterable containing path-like filenames in click.edit
• normalize path-like values with os.fspath before invoking the editor
• cover both runtime behavior and static typing

Why

click.edit(filename=Path(...)) was rejected by type checkers and treated the path as an iterable at runtime. This makes the public API consistent with other Click file APIs that already accept path-like objects.

Fixes #2869

Validation

• uv run --frozen pytest -q — 1832 passed, 95 skipped, 1 xfailed
• uv run --frozen ruff check src tests
• uv run --frozen mypy tests/typing/typing_termui.py
• git diff --check

[arturict]

Closing after finding the project's maintainer guidance that AI-generated contributions are not wanted. Sorry for missing that before opening this draft.