fix(ci): add sqlalchemy>=2.0.0 to pip install step (closes #293)

test_audit_ledger.py imports sqlalchemy directly (line 42).
Without an explicit sqlalchemy install, pip dependency resolution can
omit it when pytest/pytest-asyncio/pytest-cov are installed as a
separate step after requirements.txt.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -365,7 +365,7 @@ jobs:
           cache: pip
           cache-dependency-path: workspace/requirements.txt
       - if: needs.changes.outputs.python == 'true'
-        run: pip install -r requirements.txt pytest pytest-asyncio pytest-cov
+        run: pip install -r requirements.txt pytest pytest-asyncio pytest-cov sqlalchemy>=2.0.0
       # Coverage flags + fail-under floor moved into workspace/pytest.ini
       # (issue #1817) so local `pytest` and CI use identical config.
       - if: needs.changes.outputs.python == 'true'