google: parse docstrings that open with a section title (#115)

[HardMax71]

Fixes GH-115. A Google docstring with no summary line, opening straight with Args:, came back with zero params: inspect.cleandoc strips only the first line and dedents the rest, so the entries ended up flush with the title, the section was cut empty and GoogleParser.parse raised ParseError. In auto mode that is swallowed and the REST parse with nothing in it wins.

The parser now pushes a first-line title below a newline before cleandoc, so the title is dedented together with its entries. Docstrings with a summary or with a blank first line are untouched. Numpydoc and reST never had the problem since their entries sit at the title's indent.

Tests: a params and a returns case in test_google.py, and the auto-detection case in test_parser.py. Suite green on 3.8 and 3.12, pre-commit tools clean.

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