python-sdk: expose canonical app-server types (2026-03-16)

Remove the SDK alias/result layers so the wrapper surface returns canonical generated app-server models directly.

- delete public type alias modules and regenerate v2_all.py against current schema
- return InitializeResponse from metadata and generated Turn from run()
- update docs, examples, notebook, and tests to use canonical generated models and repo-only text extraction helpers

Validation:
- PYTHONPATH=sdk/python/src python3 -m pytest sdk/python/tests
- GH_TOKEN="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" 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/docs/faq.md

@@ -8,7 +8,7 @@
 
 ## `run()` vs `stream()`
 
-- `Turn.run()` / `AsyncTurn.run()` is the easiest path. It consumes events until completion and returns `TurnResult`.
+- `Turn.run()` / `AsyncTurn.run()` is the easiest path. It consumes events until completion and returns the canonical generated app-server `Turn` model.
 - `Turn.stream()` / `AsyncTurn.stream()` yields raw notifications (`Notification`) so you can react event-by-event.
 
 Choose `run()` for most apps. Choose `stream()` for progress UIs, custom timeout logic, or custom parsing.
@@ -91,5 +91,5 @@ Do not blindly retry all errors. For `InvalidParamsError` or `MethodNotFoundErro
 
 - Starting a new thread for every prompt when you wanted continuity.
 - Forgetting to `close()` (or not using context managers).
-- Ignoring `TurnResult.status` and `TurnResult.error`.
+- Assuming `run()` returns extra SDK-only fields instead of the generated `Turn` model.
 - Mixing SDK input classes with raw dicts incorrectly.