feat(api): add LLM model configurations endpoint and schemas

- Introduce new API route `/access` for managing LLM model configurations
- Add LLMModelConfig model to database models
- Include comprehensive schemas for LLM model config CRUD operations
- Register new router with tags for LLM Model Configurations

gns3server/api/routes/controller/__init__.py

@@ -22,6 +22,7 @@ from . import computes
 from . import drawings
 from . import gns3vm
 from . import links
+from . import llm_model_configs
 from . import nodes
 from . import projects
 from . import snapshots
@@ -145,3 +146,9 @@ router.include_router(
     prefix="/gns3vm",
     tags=["GNS3 VM"]
 )
+
+router.include_router(
+    llm_model_configs.router,
+    prefix="/access",
+    tags=["LLM Model Configurations"]
+)