fix: register provider model name and HF alias in run.yaml (#1304)

Each model known to the system has two identifiers: 

- the `provider_resource_id` (what the provider calls it) -- e.g.,
`accounts/fireworks/models/llama-v3p1-8b-instruct`
- the `identifier` (`model_id`) under which it is registered and gets
routed to the appropriate provider.

We have so far used the HuggingFace repo alias as the standardized
identifier you can use to refer to the model. So in the above example,
we'd use `meta-llama/Llama-3.1-8B-Instruct` as the name under which it
gets registered. This makes it convenient for users to refer to these
models across providers.

However, we forgot to register the _actual_ provider model ID also. You
should be able to route via `provider_resource_id` also, of course.

This change fixes this (somewhat grave) omission.

*Note*: this change is additive -- more aliases work now compared to
before.

## Test Plan

Run the following for distro=(ollama fireworks together)
```
LLAMA_STACK_CONFIG=$distro \
   pytest -s -v tests/client-sdk/inference/test_text_inference.py \
   --inference-model=meta-llama/Llama-3.1-8B-Instruct --vision-inference-model=""
```

llama_stack/templates/template.py

@@ -24,9 +24,33 @@ from llama_stack.distribution.datatypes import (
 )
 from llama_stack.distribution.distribution import get_provider_registry
 from llama_stack.distribution.utils.dynamic import instantiate_class_type
+from llama_stack.providers.utils.inference.model_registry import ProviderModelEntry
 from llama_stack.providers.utils.kvstore.config import SqliteKVStoreConfig
 
 
+def get_model_registry(available_models: Dict[str, List[ProviderModelEntry]]) -> List[ModelInput]:
+    models = []
+    for provider_id, entries in available_models.items():
+        for entry in entries:
+            ids = [entry.provider_model_id] + entry.aliases
+            for model_id in ids:
+                models.append(
+                    ModelInput(
+                        model_id=model_id,
+                        provider_model_id=entry.provider_model_id,
+                        provider_id=provider_id,
+                        model_type=entry.model_type,
+                        metadata=entry.metadata,
+                    )
+                )
+    return models
+
+
+class DefaultModel(BaseModel):
+    model_id: str
+    doc_string: str
+
+
 class RunConfigSettings(BaseModel):
     provider_overrides: Dict[str, List[Provider]] = Field(default_factory=dict)
     default_models: Optional[List[ModelInput]] = None
@@ -110,7 +134,7 @@ class DistributionTemplate(BaseModel):
     run_config_env_vars: Optional[Dict[str, Tuple[str, str]]] = None
     container_image: Optional[str] = None
 
-    default_models: Optional[List[ModelInput]] = None
+    available_models_by_provider: Optional[Dict[str, List[ProviderModelEntry]]] = None
 
     def build_config(self) -> BuildConfig:
         return BuildConfig(
@@ -148,13 +172,32 @@ class DistributionTemplate(BaseModel):
             autoescape=True,
         )
         template = env.from_string(template)
+
+        default_models = []
+        if self.available_models_by_provider:
+            has_multiple_providers = len(self.available_models_by_provider.keys()) > 1
+            for provider_id, model_entries in self.available_models_by_provider.items():
+                for model_entry in model_entries:
+                    doc_parts = []
+                    if model_entry.aliases:
+                        doc_parts.append(f"aliases: {', '.join(model_entry.aliases)}")
+                    if has_multiple_providers:
+                        doc_parts.append(f"provider: {provider_id}")
+
+                    default_models.append(
+                        DefaultModel(
+                            model_id=model_entry.provider_model_id,
+                            doc_string=f"({' -- '.join(doc_parts)})" if doc_parts else "",
+                        )
+                    )
+
         return template.render(
             name=self.name,
             description=self.description,
             providers=self.providers,
             providers_table=providers_table,
             run_config_env_vars=self.run_config_env_vars,
-            default_models=self.default_models,
+            default_models=default_models,
         )
 
     def save_distribution(self, yaml_output_dir: Path, doc_output_dir: Path) -> None: