Add application setup and test infrastructure

Application Configuration:
- FastAPI application factory pattern
- CORS middleware for cross-origin support
- Global exception handlers for consistent error responses
  - AppException handler for custom errors
  - RequestValidationError handler for Pydantic validation
  - General exception handler for unexpected errors
- Lifespan management for startup/shutdown events
- Router registration for all API endpoints
- OpenAPI schema with interactive documentation

Models Service:
- Integration with ModelRegistry
- List available models endpoint
- Model capability discovery

Test Infrastructure:
- Pytest configuration with async support
- Test client fixtures for sync and async testing
- Comprehensive main application tests (14 tests):
  - App creation and metadata
  - Router registration verification
  - CORS middleware and functionality
  - Exception handler registration and behavior
  - Lifespan event handling
  - OpenAPI schema generation
  - Documentation accessibility
  - Validation error handling
- Models API tests (2 tests)
- Total: 95 tests, 78.95% coverage

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/models/test_router.py

@@ -9,23 +9,30 @@ from fastapi.testclient import TestClient
 def test_list_models(client: TestClient) -> None:
     """Test listing available models."""
     response = client.get("/v1/models")
-    
+
     assert response.status_code == 200
     data = response.json()
-    
+
     # Verify response structure
     assert data["object"] == "list"
     assert "data" in data
     assert isinstance(data["data"], list)
-    assert len(data["data"]) > 0
-    
+
+    # Should have both models from registry
+    assert len(data["data"]) == 2
+
+    # Check for expected model IDs
+    model_ids = [m["id"] for m in data["data"]]
+    assert "lorem-tester" in model_ids
+    assert "tatlock" in model_ids
+
     # Verify model structure
-    model = data["data"][0]
-    assert model["object"] == "model"
-    assert "id" in model
-    assert model["id"] == "mistral-nemo:latest"
-    assert "created" in model
-    assert model["owned_by"] == "system"
+    for model in data["data"]:
+        assert model["object"] == "model"
+        assert "id" in model
+        assert "created" in model
+        assert "owned_by" in model
+        assert model["owned_by"] == "tatlock"
 
 
 @pytest.mark.unit