fix(server): map provider names to registry keys for /v1/models

The model registry from models.dev uses 'google' and 'xai' as provider
IDs, but internal providers use 'gemini' and 'grok'. Added mapping so
all provider models appear in the listing.

src/server/mod.rs

@@ -47,8 +47,15 @@ async fn list_models(
     for provider in &providers {
         let provider_name = provider.name();
 
+        // Map internal provider names to registry provider IDs
+        let registry_key = match provider_name {
+            "gemini" => "google",
+            "grok" => "xai",
+            _ => provider_name,
+        };
+
         // Find this provider's models in the registry
-        if let Some(provider_info) = registry.providers.get(provider_name) {
+        if let Some(provider_info) = registry.providers.get(registry_key) {
             for (model_id, meta) in &provider_info.models {
                 // Skip disabled models via the config cache
                 if let Some(cfg) = state.model_config_cache.get(model_id).await {