Add Python SDK public API and examples (#14446)

## TL;DR
WIP esp the examples

Thin the Python SDK public surface so the wrapper layer returns
canonical app-server generated models directly.

- keeps `Codex` / `AsyncCodex` / `Thread` / `Turn` and input helpers,
but removes alias-only type layers and custom result models
- `metadata` now returns `InitializeResponse` and `run()` returns the
generated app-server `Turn`
- updates docs, examples, notebook, and tests to use canonical generated
types and regenerates `v2_all.py` against current schema
- keeps the pinned runtime-package integration flow and real integration
coverage

  ## Validation
  - `PYTHONPATH=sdk/python/src python3 -m pytest sdk/python/tests`
- `GH_TOKEN="$(gh auth token)" RUN_REAL_CODEX_TESTS=1
PYTHONPATH=sdk/python/src python3 -m pytest sdk/python/tests -rs`

---------

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

sdk/python/src/codex_app_server/__init__.py

@@ -1,10 +1,111 @@
+from .async_client import AsyncAppServerClient
 from .client import AppServerClient, AppServerConfig
-from .errors import AppServerError, JsonRpcError, TransportClosedError
+from .errors import (
+    AppServerError,
+    AppServerRpcError,
+    InternalRpcError,
+    InvalidParamsError,
+    InvalidRequestError,
+    JsonRpcError,
+    MethodNotFoundError,
+    ParseError,
+    RetryLimitExceededError,
+    ServerBusyError,
+    TransportClosedError,
+    is_retryable_error,
+)
+from .generated.v2_all import (
+    AskForApproval,
+    Personality,
+    PlanType,
+    ReasoningEffort,
+    ReasoningSummary,
+    SandboxMode,
+    SandboxPolicy,
+    ServiceTier,
+    ThreadItem,
+    ThreadForkParams,
+    ThreadListParams,
+    ThreadResumeParams,
+    ThreadSortKey,
+    ThreadSourceKind,
+    ThreadStartParams,
+    ThreadTokenUsageUpdatedNotification,
+    TurnCompletedNotification,
+    TurnStartParams,
+    TurnStatus,
+    TurnSteerParams,
+)
+from .models import InitializeResponse
+from .api import (
+    AsyncCodex,
+    AsyncThread,
+    AsyncTurnHandle,
+    Codex,
+    ImageInput,
+    Input,
+    InputItem,
+    LocalImageInput,
+    MentionInput,
+    SkillInput,
+    TextInput,
+    Thread,
+    TurnHandle,
+)
+from .retry import retry_on_overload
+
+__version__ = "0.2.0"
 
 __all__ = [
+    "__version__",
     "AppServerClient",
+    "AsyncAppServerClient",
     "AppServerConfig",
+    "Codex",
+    "AsyncCodex",
+    "Thread",
+    "AsyncThread",
+    "TurnHandle",
+    "AsyncTurnHandle",
+    "InitializeResponse",
+    "Input",
+    "InputItem",
+    "TextInput",
+    "ImageInput",
+    "LocalImageInput",
+    "SkillInput",
+    "MentionInput",
+    "ThreadItem",
+    "ThreadTokenUsageUpdatedNotification",
+    "TurnCompletedNotification",
+    "AskForApproval",
+    "Personality",
+    "PlanType",
+    "ReasoningEffort",
+    "ReasoningSummary",
+    "SandboxMode",
+    "SandboxPolicy",
+    "ServiceTier",
+    "ThreadStartParams",
+    "ThreadResumeParams",
+    "ThreadListParams",
+    "ThreadSortKey",
+    "ThreadSourceKind",
+    "ThreadForkParams",
+    "TurnStatus",
+    "TurnStartParams",
+    "TurnSteerParams",
+    "retry_on_overload",
     "AppServerError",
-    "JsonRpcError",
     "TransportClosedError",
+    "JsonRpcError",
+    "AppServerRpcError",
+    "ParseError",
+    "InvalidRequestError",
+    "MethodNotFoundError",
+    "InvalidParamsError",
+    "InternalRpcError",
+    "ServerBusyError",
+    "RetryLimitExceededError",
+    "is_retryable_error",
 ]