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/examples/07_image_and_text/async.py

@@ -5,7 +5,12 @@ _EXAMPLES_ROOT = Path(__file__).resolve().parents[1]
 if str(_EXAMPLES_ROOT) not in sys.path:
     sys.path.insert(0, str(_EXAMPLES_ROOT))
 
-from _bootstrap import ensure_local_sdk_src, runtime_config
+from _bootstrap import (
+    assistant_text_from_turn,
+    ensure_local_sdk_src,
+    find_turn_by_id,
+    runtime_config,
+)
 
 ensure_local_sdk_src()
 
@@ -26,9 +31,11 @@ async def main() -> None:
             ]
         )
         result = await turn.run()
+        persisted = await thread.read(include_turns=True)
+        persisted_turn = find_turn_by_id(persisted.thread.turns, result.id)
 
         print("Status:", result.status)
-        print(result.text)
+        print(assistant_text_from_turn(persisted_turn))
 
 
 if __name__ == "__main__":