Allow bytes-like inputs in MarkItDown.convert

[lavish0000]

Closes #287

Summary:

• accept bytes, bytearray, and memoryview inputs in MarkItDown.convert()
• route bytes-like inputs through io.BytesIO so they follow the existing stream conversion path
• add a regression test covering all supported bytes-like inputs

Testing:

• uv run --project packages/markitdown --with pytest,mypy python -m pytest packages/markitdown/tests/test_module_misc.py -k 'bytes_like or input_as_strings'
• uv run --project packages/markitdown --with ruff python -m ruff check packages/markitdown/src/markitdown/_markitdown.py packages/markitdown/tests/test_module_misc.py
• uv run --project packages/markitdown --with ruff python -m ruff format --check packages/markitdown/src/markitdown/_markitdown.py packages/markitdown/tests/test_module_misc.py

Note:

• running targeted mypy against this package in this checkout still surfaces pre-existing unrelated issues in untouched files, so I limited type-check validation to the touched path plus the regression test.

[lavish0000]

@microsoft-github-policy-service agree

[lavish0000]

@microsoft-github-policy-service agree