[5/8] Rename Python SDK package to openai-codex (#21905)

## Why

The SDK should publish under the reserved public distribution name
`openai-codex`, and its import module should match that name in the
Python style. Since package names can contain hyphens but import modules
cannot, the public import path becomes `openai_codex`.

Keeping the rename separate from the public API surface change makes the
naming change easy to review and avoids mixing it with API curation.

## What

- Rename the SDK distribution from `openai-codex-app-server-sdk` to
`openai-codex`.
- Rename the import package from `codex_app_server` to `openai_codex`.
- Keep the runtime wheel as the separate `openai-codex-cli-bin`
dependency.
- Update docs, examples, notebooks, artifact scripts, lockfile metadata,
and tests for the new distribution/module names.

## Stack

1. #21891 `[1/8]` Pin Python SDK runtime dependency
2. #21893 `[2/8]` Generate Python SDK types from pinned runtime
3. #21895 `[3/8]` Run Python SDK tests in CI
4. #21896 `[4/8]` Define Python SDK public API surface
5. This PR `[5/8]` Rename Python SDK package to `openai-codex`
6. #21910 `[6/8]` Add high-level Python SDK approval mode
7. #22014 `[7/8]` Add Python SDK app-server integration harness
8. #22021 `[8/8]` Add Python SDK Ruff formatting

## Verification

- Updated package metadata and public API tests to assert the
distribution and import names.

Co-authored-by: Codex <noreply@openai.com>

sdk/python/docs/getting-started.md

@@ -24,7 +24,7 @@ Requirements:
 ## 2) Run your first turn (sync)
 
 ```python
-from codex_app_server import Codex
+from openai_codex import Codex
 
 with Codex() as codex:
     server = codex.metadata.serverInfo
@@ -50,7 +50,7 @@ What happened:
 ## 3) Continue the same thread (multi-turn)
 
 ```python
-from codex_app_server import Codex
+from openai_codex import Codex
 
 with Codex() as codex:
     thread = codex.thread_start(model="gpt-5.4", config={"model_reasoning_effort": "high"})
@@ -69,7 +69,7 @@ initializes lazily, and context entry makes startup/shutdown explicit.
 
 ```python
 import asyncio
-from codex_app_server import AsyncCodex
+from openai_codex import AsyncCodex
 
 
 async def main() -> None:
@@ -85,7 +85,7 @@ asyncio.run(main())
 ## 5) Resume an existing thread
 
 ```python
-from codex_app_server import Codex
+from openai_codex import Codex
 
 THREAD_ID = "thr_123"  # replace with a real id
 
@@ -101,7 +101,7 @@ The convenience wrappers live at the package root. Public app-server value and
 event types live under:
 
 ```python
-from codex_app_server.types import ThreadReadResponse, Turn, TurnStatus
+from openai_codex.types import ThreadReadResponse, Turn, TurnStatus
 ```
 
 ## 7) Next stops