* ci: add ruff + mypy to the Python CI job and fix pyproject tool config
The python-tests job runs pytest but not lint/type checks, and the ruff
and mypy configuration in pyproject.toml was silently broken, so neither
tool could run at all.
- add ruff and mypy steps to the existing python-tests job
- fix invalid pyproject keys: [tool.ruff] src-path -> src,
[tool.mypy] src_paths -> mypy_path
- ignore ruff UP042 (the (str, Enum) mixin is intentional)
- resolve ruff findings (unused/unsorted imports) across src and tests
- fix mypy errors in tools/executor.py and prompt/builder.py
* fix(ci): satisfy Python lint after main refresh
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Co-authored-by: haelyra <49814733+haelyra@users.noreply.github.com>
