Fix deployment URL to use actual Space domain instead of HF page

CRITICAL BUG FIX: The deployer was returning the HuggingFace Space page URL
(https://huggingface.co/spaces/{space_id}) instead of the actual deployment
endpoint URL. This caused the base deployer to continuously poll because the
health check was hitting the HF page instead of the deployment server.

Changes:
- Extract the actual domain from runtime.raw['domains']
- Construct proper deployment URL: https://{domain}
- Only set URL when status is RUNNING (follows GCP/AWS pattern)
- URL is None for non-RUNNING states

Example:
- Before: https://huggingface.co/spaces/zenml/zenml-weather_agent-5917ffec
- After:  https://zenml-zenml-weather_agent-5917ffec.hf.space

This allows the base deployer's health check to succeed and stop polling
once the deployment is fully ready.

Author: claude

src/zenml/integrations/huggingface/deployers/huggingface_deployer.py

@@ -529,9 +529,19 @@ def do_get_deployment_state(
                 # Unknown/future stages
                 status = DeploymentStatus.UNKNOWN
 
+            # Get deployment URL from Space domains (only available when RUNNING)
+            url = None
+            if status == DeploymentStatus.RUNNING and runtime.raw.get(
+                "domains"
+            ):
+                # Extract the first domain (primary domain for the Space)
+                domains = runtime.raw.get("domains", [])
+                if domains and domains[0].get("domain"):
+                    url = f"https://{domains[0]['domain']}"
+
             return DeploymentOperationalState(
                 status=status,
-                url=f"https://huggingface.co/spaces/{space_id}",
+                url=url,
                 metadata={
                     "space_id": space_id,
                     "external_state": runtime.stage,