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/imago_client/client.py

@@ -0,0 +1,64 @@
+"""
+Main client for the Imago SDK.
+"""
+from typing import Optional, Any
+import httpx
+
+from .resources.images import ImagesResource
+from .resources.ai import AIResource
+from .resources.auth import AuthResource
+
+class HubClient:
+    """
+    Main asynchronous client for interacting with the Imago backend API.
+    
+    Example:
+        async with HubClient("http://localhost:8000", api_key="my-key") as client:
+            image = await client.images.get(1)
+    """
+
+    def __init__(
+        self,
+        base_url: str,
+        api_key: Optional[str] = None,
+        timeout: float = 30.0,
+        **kwargs: Any
+    ):
+        """
+        Initializes the HubClient.
+        
+        Args:
+            base_url: The root URL of the Imago API.
+            api_key: The X-API-Key used for authentication.
+            timeout: Default timeout for requests.
+            kwargs: Additional arguments passed to httpx.AsyncClient.
+        """
+        self.base_url = base_url.rstrip('/')
+        self.api_key = api_key
+        
+        headers = kwargs.pop("headers", {})
+        if api_key:
+            headers["X-API-Key"] = api_key
+            
+        self._http_client = httpx.AsyncClient(
+            base_url=self.base_url,
+            headers=headers,
+            timeout=timeout,
+            **kwargs
+        )
+        
+        # Initialize resources
+        self.images = ImagesResource(self._http_client)
+        self.ai = AIResource(self._http_client)
+        self.auth = AuthResource(self._http_client)
+
+    async def __aenter__(self) -> "HubClient":
+        await self._http_client.__aenter__()
+        return self
+
+    async def __aexit__(self, exc_type, exc_val, exc_tb) -> None:
+         await self._http_client.__aexit__(exc_type, exc_val, exc_tb)
+
+    async def close(self) -> None:
+         """Closes the underlying HTTP client."""
+         await self._http_client.aclose()