docs: Mintlify MDX docs + docs.json; bump Speakeasy to 1.787.0 (#382)

docs/overview.mdx

@@ -0,0 +1,37 @@
+---
+title: "OpenRouter Python SDK"
+sidebarTitle: "Overview"
+description: "Python SDK for building AI features against 400+ models through OpenRouter."
+---
+
+The OpenRouter Python SDK gives you type-safe access to 400+ models across
+providers through a single unified API, with both sync and async clients.
+
+## Installation
+
+```bash
+pip install openrouter
+```
+
+## Quickstart
+
+```python
+from openrouter import OpenRouter
+import os
+
+with OpenRouter(
+    api_key=os.getenv("OPENROUTER_API_KEY", ""),
+) as open_router:
+    res = open_router.chat.send(
+        messages=[
+            {"content": "What is the capital of France?", "role": "user"},
+        ],
+        stream=False,
+    )
+    print(res)
+```
+
+## API reference
+
+Browse the API reference for each resource in the sidebar. Type definitions for
+every request, response, and model are linked inline from each resource page.