Support for raw query execution (read only queries)

[krmahadevan]

Closes #346

[krmahadevan]

@tirth8205

CI Failures — Pre-existing on main, not caused by this PR

All CI failures in this PR exist on the main branch independently of these changes. The last 3 CI runs on main (before this PR was raised) all show failure.

Root causes in the upstream repo:

1. Lint (N999) — 10 files with spaces in their names (analysis 2.py, enrich 2.py, enrich 3.py, etc.) exist in code_review_graph/ on main. Ruff rejects them as invalid module
   names.
2. Type-check — main.py:945: "FastMCP[Any]" has no attribute "_tool_manager" — this is in main.py, unrelated to any file in this PR.
3. Tests — AttributeError: 'FastMCP' object has no attribute '_tool_manager' and Java multilang assertion failures — all in pre-existing test files, none touched by this PR.

This PR only changes: code_review_graph/query.py, code_review_graph/cli.py, tests/test_query.py, pyproject.toml, docs/COMMANDS.md, uv.lock — all of which pass lint, type-check,
and tests cleanly in the local environment (43/43 tests passing).