Release Tau 0.3.2

[alejandro-ao]

Description

Prepare Tau 0.3.2 for release.

• bump the package and lockfile version from 0.3.1 to 0.3.2
• add structured 0.3.2 release notes for the OpenAI Codex model-catalog fix
• update the sidebar version assertion

Checks

• uv run pytest — 1145 passed
• uv run ruff check .
• uv run ruff format --check .
• uv run mypy
• uv build --out-dir /tmp/tau-release-0.3.2-dist
• cd website && hugo --minify && npx --yes pagefind@latest --site public

Release plan

After this PR merges, publish GitHub Release v0.3.2 from the merge commit. The release workflow will build and publish tau-ai==0.3.2 to PyPI.