[codex] Add independent beta release for the Python SDK (#24828)

## Why

`openai-codex` needs a beta release lifecycle without requiring beta
releases of its pinned runtime package. Previously, SDK staging rewrote
its runtime dependency to the SDK version, which made an SDK-only beta
impossible.

## What changed

- Set the initial SDK beta version to `0.1.0b1` and pin it to published
stable `openai-codex-cli-bin==0.132.0`.
- Decoupled SDK release staging from runtime versioning so it preserves
the reviewed exact runtime pin.
- Added a `python-v*` tag workflow that builds and publishes only
`openai-codex` through PyPI trusted publishing.
- Removed the Beta classifier from runtime package metadata for future
runtime publications.
- Regenerated protocol-derived SDK models from the selected stable
runtime package.

`0.132.0` is the newest stable runtime admitted by the checked-in
dependency date fence and retains the Linux wheel family currently used
by SDK CI.

## Release setup

Before pushing `python-v0.1.0b1`, configure PyPI trusted publishing for
the `openai-codex` project with workflow `python-sdk-release.yml`,
environment `pypi`, and job `publish-python-sdk`.

## Validation

- `uv run --frozen --extra dev ruff check src/openai_codex scripts
examples tests`
- Parsed `.github/workflows/python-sdk-release.yml` with PyYAML.
- Built staged release artifacts locally:
`openai_codex-0.1.0b1-py3-none-any.whl` and
`openai_codex-0.1.0b1.tar.gz`.
- Verified wheel metadata pins `openai-codex-cli-bin==0.132.0`.
- Tests are deferred to online CI for this PR.

sdk/python/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "openai-codex"
-version = "0.131.0a4"
+version = "0.1.0b1"
 description = "Python SDK for Codex app-server v2"
 readme = "README.md"
 requires-python = ">=3.10"
@@ -22,7 +22,7 @@ classifiers = [
   "Programming Language :: Python :: 3.13",
   "Topic :: Software Development :: Libraries :: Python Modules",
 ]
-dependencies = ["pydantic>=2.12", "openai-codex-cli-bin==0.131.0a4"]
+dependencies = ["pydantic>=2.12", "openai-codex-cli-bin==0.132.0"]
 
 [project.urls]
 Homepage = "https://github.com/openai/codex"
@@ -86,10 +86,10 @@ combine-as-imports = true
 
 [tool.uv]
 exclude-newer = "7 days"
-exclude-newer-package = { openai-codex-cli-bin = "2026-05-10T00:00:00Z" }
+exclude-newer-package = { openai-codex-cli-bin = "2026-05-20T21:00:00Z" }
 index-strategy = "first-index"
 
 [tool.uv.pip]
 exclude-newer = "7 days"
-exclude-newer-package = { openai-codex-cli-bin = "2026-05-10T00:00:00Z" }
+exclude-newer-package = { openai-codex-cli-bin = "2026-05-20T21:00:00Z" }
 index-strategy = "first-index"