fix: remove phantom aioodbc extra

[cofin]

Summary

• remove the unbacked aioodbc optional extra and pytest marker
• correct the installation extras table so documented package groups match public pyproject.toml extras
• add a parity test that keeps installation docs aligned with optional dependencies

Tests

• uv run pytest tests/unit/test_docs_extras_parity.py -q --tb=short
• uv lock --check
• uv run ruff check tests/unit/test_docs_extras_parity.py
• uv run ruff format --check tests/unit/test_docs_extras_parity.py

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.68%. Comparing base (b4a7d05) to head (7c0bd9c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #569   +/-   ##
=======================================
  Coverage   75.68%   75.68%           
=======================================
  Files         449      449           
  Lines       59986    59986           
  Branches     9144     9144           
=======================================
  Hits        45398    45398           
  Misses      11657    11657           
  Partials     2931     2931           

Flag	Coverage Δ
integration	59.37% <ø> (ø)
py3.10	74.08% <ø> (ø)
py3.11	74.09% <ø> (ø)
py3.12	74.09% <ø> (ø)
py3.13	74.09% <ø> (ø)
py3.14	74.87% <ø> (ø)
unit	61.81% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.