[ac1982]

Fixes #195.

Annotate each variadic OSC callback argument with the existing ArgValue alias in the dispatcher guide and Dispatcher.map docstring. The previous *args: List[Any] annotation makes the documented float calls fail type checking. Keep fixed arguments typed as a separate list, explain that distinction, and make the callback signature examples valid Python and ReST.

Validation on Python 3.12/Linux ARM64:

• The original guide's callback rejects two float arguments in mypy; the corrected example passes and runs over actual loopback UDP.
• All four callback signatures work with real encoded packets, both synchronously and asynchronously, including scalars, blobs, nil, MIDI and nested arrays.
• 181 tests pass; Ruff check/format, mypy on 42 files, package build and an isolated installed-wheel typing check pass.
• Changed-file pre-commit checks pass. Full pre-commit has the same eight mypy errors on the unmodified baseline because its isolated hook lacks pytest; the project environment's mypy check passes.
• Sphinx diagnostics decrease from 15 to 9, removing the map signature rendering errors. Remaining baseline errors/warnings mean the full documentation build still fails warnings-as-errors.

No runtime behavior changes. Other platforms and Python versions were not tested locally. Prepared with OpenAI Codex assistance.