chore(release): 0.0.3

Squash-merge lib-standardisation: adopt repo standards across packaging,
tooling, docs, and CI.

- standardize pyproject.toml (canonical packaging, lint config, extras, GSDFC pydoclint)
- add py.typed marker, modernize type hints and Google-style docstrings
- nest generated docs under docs/lib and docs/mcp; add hand-written wiki
- adopt standard Type A PyPI CI pipeline (tag==version guard + quality gate)
- promote generated CHANGELOG.md; bump version to 0.0.3

README.md

@@ -91,6 +91,9 @@ required.
 - `FileSystemPDFClient`: Local filesystem PDF access.
 - `PDFScraper`: PDF-specific content acquisition.
 - `PDFParser`: Base parser for PDF binary interpretation.
+- `FileSystemXlsxClient`: Local filesystem spreadsheet access.
+- `XlsxScraper`: XLSX-specific content acquisition.
+- `XlsxParser`: Generic string-row parser for xlsx workbooks.
 
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