feat(infrastructure): Add night-scheduler for automated Docker service shutdown

Implement dashboard-controlled night mode for automatic Docker service
management. Services are stopped at a configurable time (default 22:00)
and restarted in the morning (default 06:00).

Features:
- Python/FastAPI scheduler service (port 8096)
- Admin dashboard API routes at /api/admin/night-mode
- Toggle for enable/disable night mode
- Time picker for shutdown and startup times
- Manual start/stop buttons for immediate actions
- Excluded services (night-scheduler, nginx always run)

Files added:
- night-scheduler/scheduler.py - Main scheduler with REST API
- night-scheduler/Dockerfile - Container with Docker CLI
- night-scheduler/requirements.txt - FastAPI, Uvicorn, Pydantic
- night-scheduler/tests/test_scheduler.py - Unit tests
- admin-v2/app/api/admin/night-mode/* - API proxy routes
- .claude/rules/night-scheduler.md - Developer documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

night-scheduler/config/night-mode.json

@@ -0,0 +1,8 @@
+{
+  "enabled": false,
+  "shutdown_time": "22:00",
+  "startup_time": "06:00",
+  "last_action": null,
+  "last_action_time": null,
+  "excluded_services": ["night-scheduler", "nginx"]
+}