feat: customer frontend, Sungrow collector fixes, real data (v1.2.0)

- Add frontend/ at root (no Three.js, no Charging, green #52c41a theme)
- Fix Sungrow collector: add curPage/size params, unit conversion
- Fix station-level dedup to prevent double-counting
- Add shared token cache for API rate limit protection
- Add .githooks/pre-commit, CLAUDE.md, .gitignore
- Update docker-compose.override.yml frontend -> ./frontend
- Pin bcrypt in requirements.txt
- Add BUYOFF_RESULTS_2026-04-05.md (39/43 pass)
- Data accuracy: 0.0% diff vs iSolarCloud

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

core/backend/app/collectors/manager.py

@@ -11,6 +11,7 @@ from app.collectors.base import BaseCollector
 from app.collectors.modbus_tcp import ModbusTcpCollector
 from app.collectors.mqtt_collector import MqttCollector
 from app.collectors.http_collector import HttpCollector
+from app.collectors.sungrow_collector import SungrowCollector
 
 logger = logging.getLogger("collector.manager")
 
@@ -19,6 +20,7 @@ COLLECTOR_REGISTRY: dict[str, type[BaseCollector]] = {
     "modbus_tcp": ModbusTcpCollector,
     "mqtt": MqttCollector,
     "http_api": HttpCollector,
+    "sungrow_api": SungrowCollector,
 }