Initial commit: OpenRouter Python SDK

Auto-generated Python SDK for OpenRouter API, providing comprehensive client library with:
- Chat completions and streaming support
- Embeddings API
- Model and provider information
- API key management
- Analytics and usage tracking
- OAuth authentication flows
- Full type hints and error handling

docs/models/openairesponsesinputroleunion2.md

@@ -0,0 +1,23 @@
+# OpenAIResponsesInputRoleUnion2
+
+
+## Supported Types
+
+### `models.OpenAIResponsesInputRoleUser2`
+
+```python
+value: models.OpenAIResponsesInputRoleUser2 = /* values here */
+```
+
+### `models.OpenAIResponsesInputRoleSystem2`
+
+```python
+value: models.OpenAIResponsesInputRoleSystem2 = /* values here */
+```
+
+### `models.OpenAIResponsesInputRoleDeveloper2`
+
+```python
+value: models.OpenAIResponsesInputRoleDeveloper2 = /* values here */
+```
+