Move _get_base_url to the base provider

In order to properly support "muxing providers" like openrouter, we'll
have to tell litellm (or in future a native implementation), what server
do we want to proxy to. We were already doing that with Vllm, but since
are about to do the same for OpenRouter, let's move the `_get_base_url`
method to the base provider.

Author: jhrozek

src/codegate/providers/base.py

@@ -12,6 +12,7 @@
 
 from codegate.clients.clients import ClientType
 from codegate.codegate_logging import setup_logging
+from codegate.config import Config
 from codegate.db.connection import DbRecorder
 from codegate.pipeline.base import (
     PipelineContext,
@@ -88,6 +89,13 @@ async def process_request(
     def provider_route_name(self) -> str:
         pass
 
+    def _get_base_url(self) -> str:
+        """
+        Get the base URL from config with proper formatting
+        """
+        config = Config.get_config()
+        return config.provider_urls.get(self.provider_route_name) if config else ""
+
     async def _run_output_stream_pipeline(
         self,
         input_context: PipelineContext,

src/codegate/providers/vllm/provider.py

@@ -39,8 +39,7 @@ def _get_base_url(self) -> str:
         """
         Get the base URL from config with proper formatting
         """
-        config = Config.get_config()
-        base_url = config.provider_urls.get("vllm") if config else ""
+        base_url = super()._get_base_url()
         if base_url:
             base_url = base_url.rstrip("/")
             # Add /v1 if not present