fix(models): add alembic migration 009 for missing tables (v1.4.1)

Migration adds tables that existed in models/ but were never
included in alembic history:
- ai_ops: device_health_scores, anomaly_detections, diagnostic_reports,
  maintenance_predictions, ops_insights
- energy_strategy: tou_pricing, tou_pricing_periods, energy_strategies,
  strategy_executions, monthly_cost_reports
- weather: weather_data, weather_config
- prediction: prediction_tasks, prediction_results, optimization_schedules

Without this migration, fresh deploys would 500 on these endpoints:
- /api/v1/ai-ops/health, /ai-ops/dashboard
- /api/v1/strategy/pricing
- /api/v1/prediction/forecast
- /api/v1/weather/current

Discovered during Z-Park demo deployment on xie_openclaw1.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -20,6 +20,7 @@ from app.models.prediction import PredictionTask, PredictionResult, Optimization
 from app.models.energy_strategy import TouPricing, TouPricingPeriod, EnergyStrategy, StrategyExecution, MonthlyCostReport
 from app.models.weather import WeatherData, WeatherConfig
 from app.models.ai_ops import DeviceHealthScore, AnomalyDetection, DiagnosticReport, MaintenancePrediction, OpsInsight
+from app.models.meter import MeterReading
 
 __all__ = [
     "User", "Role", "AuditLog",
@@ -40,4 +41,5 @@ __all__ = [
     "TouPricing", "TouPricingPeriod", "EnergyStrategy", "StrategyExecution", "MonthlyCostReport",
     "WeatherData", "WeatherConfig",
     "DeviceHealthScore", "AnomalyDetection", "DiagnosticReport", "MaintenancePrediction", "OpsInsight",
+    "MeterReading",
 ]