Test suite fails with UnicodeDecodeError on Windows with non-UTF-8 locale: read_text() calls missing encoding #3244

Describe the bug

On Windows systems where the ANSI code page is not UTF-8 (e.g. Chinese-locale Windows, code page 936 / GBK), running the test suite fails with UnicodeDecodeError in two places:

1. tests/examples/conftest.py:41 - (STORIES_DIR / manifest.toml).read_text() fails during collection (8 collection errors, blocking all of tests/examples):

tests\examples\conftest.py:41: in <module>
    MANIFEST = tomllib.loads((STORIES_DIR / manifest.toml).read_text())
E   UnicodeDecodeError: 'gbk' codec can't decode byte 0x94 in position 441: illegal multibyte sequence

2. tests/examples/test_story_shape.py:30 - _parse reads story sources with path.read_text() (~70 test failures once collection succeeds):

tests\examples\test_story_shape.py:30: in _parse
    return ast.parse(path.read_text(), filename=str(path))
E   UnicodeDecodeError: 'gbk' codec can't decode byte 0x92 in position 1311: illegal multibyte sequence

Path.read_text() without an encoding argument uses locale.getpreferredencoding(), which is the ANSI code page on Windows (cp936/GBK on Chinese-locale systems, cp1252 on Western-locale systems). The files being read (manifest.toml, story sources) are UTF-8 and contain non-ASCII bytes, so decoding fails. CI does not catch this because windows-latest runners use cp1252, which happens to decode those byte sequences without raising.

Expected behavior

The test suite passes regardless of the host locale. TOML is UTF-8 by specification, and the story sources are UTF-8, so both call sites should pass encoding=utf-8 explicitly.

Environment

• OS: Windows 10 (Chinese locale, ANSI code page 936/GBK)
• Python: 3.11.14
• SDK: main @ a4f4ccd

Additional context

Fix is two one-line changes adding encoding=utf-8; PR to follow.

Disclosure: this bug was found and the fix prepared with AI assistance (Claude Code); the change has been reviewed and verified by me (full suite green on the affected machine: 5574 passed).