fix(sidecar-v2): incorporate review feedback - P0/P1 fixes

P0 fixes:
- Admin API Bearer Token auth middleware
- Encryption key missing -> CRITICAL log + sys.exit(1)
- Prometheus metrics endpoint (:9191)
- requirements.txt + Dockerfile + docker-compose.yml + systemd + nginx

P1 fixes:
- Dead code removed from _refresh_cooldowns()
- Stream detection fixed (text/event-stream only)
- Emergency passthrough (10% RPM retry before 503)
- Active health probing for backends
- SQLite daily backup loop with retention
- Chart.js CDN fallback
- Key rotation SOP document
- JSON log format support
- Deploy files: systemd unit + nginx config

BIZ-52 review re-entry

Co-authored-by: multica-agent <github@multica.ai>

services/nvidia_sidecar/Dockerfile

@@ -0,0 +1,46 @@
+# Sidecar V2 — Multi-Pool Provider Proxy
+FROM python:3.12-slim AS builder
+
+WORKDIR /app
+
+# Install dependencies
+COPY requirements.txt .
+RUN pip install --no-cache-dir --upgrade pip && \
+    pip install --no-cache-dir -r requirements.txt
+
+# Copy application code
+COPY config.py crypto.py main.py server.py proxy.py router.py \
+     pool_manager.py cooldown_manager.py rate_limiter.py __init__.py \
+     dashboard.html ./
+COPY storage/ ./storage/
+
+# Create data directory
+RUN mkdir -p /app/data /app/data/backups
+
+FROM python:3.12-slim
+
+WORKDIR /app
+
+# Copy built artifacts
+COPY --from=builder /usr/local/lib/python3.12/site-packages /usr/local/lib/python3.12/site-packages
+COPY --from=builder /app /app
+
+# Environment
+ENV SIDECAR_HOST=0.0.0.0
+ENV SIDECAR_PORT=9190
+ENV SIDECAR_METRICS_PORT=9191
+ENV SIDECAR_DB_PATH=/app/data/sidecar_v2.db
+ENV SIDECAR_BACKUP_DIR=/app/data/backups
+ENV SIDECAR_ENCRYPTION_KEY=
+ENV SIDECAR_ADMIN_TOKEN=
+ENV LOG_FORMAT=json
+ENV PYTHONUNBUFFERED=1
+
+EXPOSE 9190 9191
+
+VOLUME ["/app/data"]
+
+HEALTHCHECK --interval=30s --timeout=5s --retries=3 \
+    CMD python3 -c "import urllib.request; urllib.request.urlopen('http://localhost:9190/health')" || exit 1
+
+ENTRYPOINT ["python3", "main.py"]