fix(providers): seed llama-swap default model and fix rustfmt

Codex review: an empty `models` list makes `default_model` become ""
in `ProviderRegistry::register_with_name`, which causes onboarding
paths to persist an empty `GOOSE_MODEL` and fall back to app defaults
instead of the selected provider. Seed with `qwen3` (matching the
ollama default) so the provider has a usable placeholder until the
dynamic `/v1/models` fetch populates the real list.

Also collapse a multi-line `assert_eq!` to satisfy `cargo fmt --check`.

Author: caniko

crates/goose/src/config/declarative_providers.rs

@@ -543,11 +543,9 @@ mod tests {
         assert!(config.skip_canonical_filtering);
         assert_eq!(config.dynamic_models, Some(true));
         assert_eq!(config.supports_streaming, Some(true));
-        assert_eq!(
-            config.base_url,
-            "${LLAMA_SWAP_HOST}/v1/chat/completions"
-        );
-        assert!(config.models.is_empty());
+        assert_eq!(config.base_url, "${LLAMA_SWAP_HOST}/v1/chat/completions");
+        assert_eq!(config.models.len(), 1);
+        assert_eq!(config.models[0].name, "qwen3");
 
         let env_vars = config.env_vars.as_ref().expect("env_vars should be set");
         assert_eq!(env_vars.len(), 1);

crates/goose/src/providers/declarative/llama_swap.json

@@ -16,7 +16,9 @@
     }
   ],
   "dynamic_models": true,
-  "models": [],
+  "models": [
+    { "name": "qwen3", "context_limit": 32768 }
+  ],
   "supports_streaming": true,
   "requires_auth": false,
   "skip_canonical_filtering": true