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/chatmessagecontentitemtext.md

@@ -0,0 +1,9 @@
+# ChatMessageContentItemText
+
+
+## Fields
+
+| Field              | Type               | Required           | Description        |
+| ------------------ | ------------------ | ------------------ | ------------------ |
+| `type`             | *Literal["text"]*  | :heavy_check_mark: | N/A                |
+| `text`             | *str*              | :heavy_check_mark: | N/A                |