Better Civ Archive support (adds API) (#549)

* add CivArchive API

* Oops, missed committing this part when I updated codebase to latest version

* Adjust API for version fetching and solve the broken API (hash gives only files, not models - likely to be fixed but in the meantime...)

* add asyncio import to allow timeout cooldown

---------

Co-authored-by: Scruffy Nerf <Scruffynerf@duck.com>

py/services/service_registry.py

@@ -144,6 +144,27 @@ class ServiceRegistry:
             cls._services[service_name] = client
             logger.debug(f"Created and registered {service_name}")
             return client
+
+    @classmethod
+    async def get_civarchive_client(cls):
+        """Get or create CivArchive client instance"""
+        service_name = "civarchive_client"
+        
+        if service_name in cls._services:
+            return cls._services[service_name]
+        
+        async with cls._get_lock(service_name):
+            # Double-check after acquiring lock
+            if service_name in cls._services:
+                return cls._services[service_name]
+            
+            # Import here to avoid circular imports
+            from .civarchive_client import CivArchiveClient
+            
+            client = await CivArchiveClient.get_instance()
+            cls._services[service_name] = client
+            logger.debug(f"Created and registered {service_name}")
+            return client
     
     @classmethod
     async def get_download_manager(cls):