fix(model-registry): fallback config 更新為 deepseek-r1:14b + gemma3:4b

- model_registry._get_default_config: ollama summary llama3.2:3b → gemma3:4b
- model_registry._get_default_config: ollama default/rca → deepseek-r1:14b
- 修正 test_smart_router::test_simple_context 失敗 (斷言 gemma3:4b)
- alert_rule_engine: 移除 asyncio/time unused import
- 2026-04-09 ogt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/services/alert_rule_engine.py

@@ -20,10 +20,8 @@ OpenClaw 告警規則匹配引擎
 
 from __future__ import annotations
 
-import asyncio
 import json
 import re
-import time
 from datetime import datetime
 from functools import lru_cache
 from pathlib import Path