feat(reports): manual run/view endpoints for the night report

Add backend/routers/reports.py (registered in main.py):
- GET  /api/projects/{id}/reports/nightly/view — render the night report
  HTML inline (preview; no write, no email)
- POST /api/projects/{id}/reports/nightly/run  — build -> write
  report.html/report.json to disk -> dry-run email -> JSON result + view_url

Same entry point the scheduled morning tick will reuse. Query params:
night_date (default last night, local tz), baseline_start/end, metrics, send.
Orchestrator now also returns the rendered html for inline display.

Verified via FastAPI TestClient on real meter data (200 HTML with the computed
numbers, files written to disk, 400/404 validation paths).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/main.py

@@ -148,6 +148,10 @@ app.include_router(deployments.router)
 from backend.routers import calibration
 app.include_router(calibration.router)
 
+# Nightly sound-report pipeline (manual triggers; scheduled tick reuses run_nightly_report)
+from backend.routers import reports
+app.include_router(reports.router)
+
 # Start scheduler service and device status monitor on application startup
 from backend.services.scheduler import start_scheduler, stop_scheduler
 from backend.services.device_status_monitor import start_device_status_monitor, stop_device_status_monitor