[joe-clickhouse]

Add Python 3.15 to CI and package classifiers. Refresh locked dependencies for 3.15 compatibility, including Windows wheels.

Skip installing chDB on 3.15 because its native import can terminate Python. Keep chDB coverage on 3.10-3.14, clarify the missing-dependency warning, and document source-build requirements.

[Copilot]

🔵 Needs a closer look

Python 3.15 native-dependency compatibility and source builds need successful CI validation that was not verified in this review.

No open issues 🎉

What changed in this PR

Adds Python 3.15 support to package metadata and CI while keeping optional chDB support on Python 3.10 through 3.14.

Changes:

• Adds a Python 3.15 CI job and package classifier.
• Excludes chDB installation on Python 3.15 and later, with version-specific missing-dependency warnings and tests.
• Documents Python compatibility, source-build requirements, and updated development commands.

File	Description
tests/​test_optional_chdb.py	Tests missing-chDB warnings across Python versions.
tests/​test_chdb_tool.py	Simplifies the chDB test skip message.
README.md	Documents compatibility, native-import risks, and setup requirements.
pyproject.toml	Adds the Python 3.15 classifier and limits the chDB dependency.
mcp_clickhouse/​chdb_backend.py	Explains missing chDB on Python 3.15 and later.
CHANGELOG.md	Records Python support and dependency updates.
.github/​workflows/​ci.yaml	Adds Python 3.15 locked-dependency coverage.

_{Review effort: Balanced}