feat: v2.0 — maintenance module, AI analysis, station power fix

- Add full 检修维护中心 (6.4): 3-type work orders (消缺/巡检/抄表),
  asset management, warehouse, work plans, billing settlement
- Add AI智能分析 tab with LLM-powered diagnostics (StepFun + ZhipuAI)
- Add AI模型配置 settings page (provider, temperature, prompts)
- Fix station power accuracy: use API station total (station_power)
  instead of inverter-level computation — eliminates timing gaps
- Add 7 new DB models, 4 new API routers, 5 new frontend pages
- Migrations: 009 (maintenance expansion) + 010 (AI analysis)
- Version bump: 1.6.1 → 2.0.0

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

core/backend/app/collectors/sungrow_collector.py

@@ -87,6 +87,13 @@ class SungrowCollector(BaseCollector):
             ps_data = await self._get_station_data()
             if ps_data:
                 data.update(ps_data)
+                # Also store station-level power with a distinct data_type
+                # so dashboard can read the API total directly instead of
+                # computing from individual device readings.
+                if "power" in ps_data:
+                    data["station_power"] = ps_data["power"]
+                if "daily_energy" in ps_data:
+                    data["station_daily_energy"] = ps_data["daily_energy"]
                 self.logger.info(
                     "Station %s data: power=%.1f kW, daily=%.1f kWh",
                     self._ps_id,