Add Python app-server SDK (#14435)

## TL;DR
Bring the Python app-server SDK from `main-with-prs-13953-and-14232`
onto current `main` as a standalone SDK-only PR.

- adds the new `sdk/python` and `sdk/python-runtime` package trees
- keeps the scope to the SDK payload only, without the unrelated
branch-history or workflow changes from the source branch
- regenerates `sdk/python/src/codex_app_server/generated/v2_all.py`
against current `main` schema so the extracted SDK matches today's
protocol definitions

## Validation
- `PYTHONPATH=sdk/python/src python3 -m pytest sdk/python/tests`

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

sdk/python-runtime/README.md

@@ -0,0 +1,9 @@
+# Codex CLI Runtime for Python SDK
+
+Platform-specific runtime package consumed by the published `codex-app-server-sdk`.
+
+This package is staged during release so the SDK can pin an exact Codex CLI
+version without checking platform binaries into the repo.
+
+`codex-cli-bin` is intentionally wheel-only. Do not build or publish an sdist
+for this package.

sdk/python-runtime/hatch_build.py

@@ -0,0 +1,15 @@
+from __future__ import annotations
+
+from hatchling.builders.hooks.plugin.interface import BuildHookInterface
+
+
+class RuntimeBuildHook(BuildHookInterface):
+    def initialize(self, version: str, build_data: dict[str, object]) -> None:
+        del version
+        if self.target_name == "sdist":
+            raise RuntimeError(
+                "codex-cli-bin is wheel-only; build and publish platform wheels only."
+            )
+
+        build_data["pure_python"] = False
+        build_data["infer_tag"] = True

sdk/python-runtime/pyproject.toml

@@ -0,0 +1,45 @@
+[build-system]
+requires = ["hatchling>=1.24.0"]
+build-backend = "hatchling.build"
+
+[project]
+name = "codex-cli-bin"
+version = "0.0.0-dev"
+description = "Pinned Codex CLI runtime for the Python SDK"
+readme = "README.md"
+requires-python = ">=3.10"
+license = { text = "Apache-2.0" }
+authors = [{ name = "OpenAI" }]
+classifiers = [
+  "Development Status :: 4 - Beta",
+  "Intended Audience :: Developers",
+  "License :: OSI Approved :: Apache Software License",
+  "Programming Language :: Python :: 3",
+  "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
+  "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
+]
+
+[project.urls]
+Homepage = "https://github.com/openai/codex"
+Repository = "https://github.com/openai/codex"
+Issues = "https://github.com/openai/codex/issues"
+
+[tool.hatch.build]
+exclude = [
+  ".venv/**",
+  ".pytest_cache/**",
+  "dist/**",
+  "build/**",
+]
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/codex_cli_bin"]
+include = ["src/codex_cli_bin/bin/**"]
+
+[tool.hatch.build.targets.wheel.hooks.custom]
+
+[tool.hatch.build.targets.sdist]
+
+[tool.hatch.build.targets.sdist.hooks.custom]

sdk/python-runtime/src/codex_cli_bin/__init__.py

@@ -0,0 +1,19 @@
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+PACKAGE_NAME = "codex-cli-bin"
+
+
+def bundled_codex_path() -> Path:
+    exe = "codex.exe" if os.name == "nt" else "codex"
+    path = Path(__file__).resolve().parent / "bin" / exe
+    if not path.is_file():
+        raise FileNotFoundError(
+            f"{PACKAGE_NAME} is installed but missing its packaged codex binary at {path}"
+        )
+    return path
+
+
+__all__ = ["PACKAGE_NAME", "bundled_codex_path"]