Add admin panel, WebSocket support, and API versioning

Introduce an admin portal (React + Nginx), WebSocket routing, and
API versioning middleware with `/api/v1/` prefix deprecation.
Add master API key authentication, new Prometheus metrics for AI
token consumption and active WebSockets, and extend S3 config
with a public endpoint URL. Update test paths and fixtures to
align with the new routing structure.

sdk/README.md

@@ -0,0 +1,36 @@
+# Imago Python SDK
+
+The official Python client for interacting with the Imago backend API.
+
+## Installation
+
+```bash
+pip install imago-client
+```
+
+## Basic Usage
+
+```python
+import asyncio
+from imago_client import HubClient
+
+async def main():
+    async with HubClient("http://localhost:8000", api_key="your-api-key") as client:
+        # Upload an image
+        with open("photo.jpg", "rb") as f:
+            image = await client.images.upload(f.read(), "photo.jpg")
+            print(f"Uploaded! ID: {image.id}")
+
+            # Stream real-time pipeline events
+            stream = client.images.stream_pipeline(image.id, "your-api-key")
+            async for event in stream.stream_events():
+                print(f"Event: {event}")
+        
+        # Get processed data
+        processed = await client.images.get(image.id)
+        if processed.ai:
+            print("AI Description:", processed.ai.description)
+
+if __name__ == "__main__":
+    asyncio.run(main())
+```