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/Dockerfile

@@ -0,0 +1,30 @@
+FROM python:3.11-slim
+
+# Docker CLI installieren (für docker compose Befehle)
+RUN apt-get update && apt-get install -y \
+    curl \
+    gnupg \
+    lsb-release \
+    && curl -fsSL https://download.docker.com/linux/debian/gpg | gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg \
+    && echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/debian $(lsb_release -cs) stable" > /etc/apt/sources.list.d/docker.list \
+    && apt-get update \
+    && apt-get install -y docker-ce-cli docker-compose-plugin \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+# Python Dependencies
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Anwendung kopieren
+COPY scheduler.py .
+
+# Config-Verzeichnis
+RUN mkdir -p /config
+
+# Port für REST-API
+EXPOSE 8096
+
+# Start
+CMD ["python", "scheduler.py"]