feat!: generic defaults, dashboard fallback, PV filter fix (v1.3.0)

- Replace all hardcoded Tianpu/天普 defaults with generic "EMS Platform"
- Add energy_today fallback: query raw energy_data when daily summary empty
- Fix PV device filter to include sungrow_inverter device type
- Update APP_NAME, CUSTOMER default, SECRET_KEY, SMTP, Celery, email templates

BREAKING: CUSTOMER default changed from "tianpu" to "default"
Existing deployments with CUSTOMER=tianpu in .env are unaffected.

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

backend/app/services/simulator.py

@@ -1,4 +1,4 @@
-"""模拟数据生成器 - 为天普园区设备生成真实感的模拟数据
+"""模拟数据生成器 - 为园区设备生成真实感的模拟数据
 
 Uses physics-based solar position, Beijing weather models, cloud transients,
 temperature derating, and realistic building load patterns to produce data