feat: add Claude backend with automatic Ollama fallback (Claudification Phase 1)

All agents now prefer Claude API when ANTHROPIC_API_KEY is configured,
with automatic fallback to Ollama when offline or unconfigured. New
src/anthropic/ module provides model selection via get_model() factory.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/main.py

@@ -44,14 +44,16 @@ async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
         app_name=config.APP_NAME,
         version=config.APP_VERSION,
         environment=config.ENVIRONMENT.value,
+        prefer_cloud=config.PREFER_CLOUD_BACKEND,
+        anthropic_model=config.ANTHROPIC_MODEL,
         ollama_host=str(config.OLLAMA_HOST),
         ollama_model=config.OLLAMA_DEFAULT_MODEL,
         redis_url=config.redis_memory_url,
         log_format=config.log_format,
     )
 
-    # Initialize application (register household members, etc.)
-    initialize_application()
+    # Initialize application (check Claude health, register household members, etc.)
+    await initialize_application()
 
     yield