Add AUTHORS.md

Three credits in the project's history:

- Original 2016-2017 implementation, fully mine (at the University of
  Jyväskylä).
- MSVC compatibility by David Caron in 2018 (commit d82044b): Windows
  compiler flags, popcount.h MSVC-intrinsics shim, and the small
  portability fixes in the .pyx sources that let the codebase compile
  under Visual Studio. Never verified end-to-end at runtime — the
  diagnostic CI run this pass likely took it to a working Windows
  import for the first time — but the compile-level MSVC groundwork
  is his.
- 2026 modernization as an AI-pair-programming pass, with Claude
  (Anthropic) as the pair partner, matching the wording convention in
  mcpyrate's AUTHORS.md.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Technologicat

AUTHORS.md

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+# Authors
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+- Original [`wlsqm`](https://github.com/Technologicat/python-wlsqm) by Juha Jeronen (@Technologicat), 2016–2017, at the University of Jyväskylä. BSD 2-Clause license.
+
+- MSVC compatibility (commit [d82044b](https://github.com/Technologicat/python-wlsqm/commit/d82044bc83e9d2ecdeb0b0a44d3e4a8645f7a144), 2018) by David Caron (@davidcaron): Windows compiler flags, `popcount.h` MSVC-intrinsics shim, and a handful of small portability fixes in the `.pyx` sources so the codebase compiles cleanly under Visual Studio in addition to GCC.
+
+- Modernization for Python 3.11–3.14 by Juha Jeronen, with [Claude](https://claude.ai/) (Anthropic) as AI pair programmer, 2026.