feat(hardening): M-Hard 6 + 7 — PostgreSQL backend + production server infra

M-Hard 6: PostgreSQL Storage Backend
- @shade/storage-postgres with PostgresStorage + PostgresPrekeyStore
- Drizzle-style raw SQL ensureClientTables / ensurePrekeyServerTables
- All tables prefixed `shade_` to avoid collisions in shared databases
- DELETE ... FOR UPDATE SKIP LOCKED for concurrent OTPK consumption
- Tests skip gracefully without SHADE_TEST_PG_URL, run against real PG when set

M-Hard 7: Production Server Infrastructure
- Structured JSON logger (logger.ts) — SHADE_LOG_LEVEL configurable
- Health endpoints (/health, /healthz, /ready) — Kubernetes-friendly
- Prometheus metrics (/metrics) — counters, histograms, middleware
- Graceful shutdown with SIGTERM/SIGINT handlers + store close
- Production Dockerfile with non-root user, healthcheck, multi-stage build
- docker-compose.yml example for Dokploy with optional PostgreSQL

193 tests passing, 0 failures.

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

packages/shade-server/docker-compose.yml

@@ -0,0 +1,50 @@
+# Shade Prekey Server — Dokploy/Docker Compose deployment
+#
+# Usage:
+#   docker compose up -d
+#
+# The SQLite database is persisted to a named volume so data survives
+# container restarts. To use PostgreSQL instead, set SHADE_PREKEY_PG_URL
+# and uncomment the depends_on / postgres service block below.
+
+services:
+  shade-prekey:
+    build:
+      context: ../..
+      dockerfile: packages/shade-server/Dockerfile
+    image: shade-prekey-server:latest
+    restart: unless-stopped
+    ports:
+      - "3900:3900"
+    volumes:
+      - shade-data:/data
+    environment:
+      - PORT=3900
+      - SHADE_PREKEY_DB_PATH=/data/shade-prekeys.db
+      - SHADE_LOG_LEVEL=info
+    healthcheck:
+      test: ["CMD", "curl", "-fsS", "http://localhost:3900/health"]
+      interval: 30s
+      timeout: 5s
+      start_period: 10s
+      retries: 3
+    # Uncomment for PostgreSQL backend:
+    # depends_on:
+    #   - postgres
+    # environment:
+    #   - SHADE_PREKEY_PG_URL=postgres://shade:shade@postgres:5432/shade
+
+  # Uncomment to use PostgreSQL instead of SQLite:
+  # postgres:
+  #   image: postgres:16-alpine
+  #   restart: unless-stopped
+  #   environment:
+  #     - POSTGRES_USER=shade
+  #     - POSTGRES_PASSWORD=shade
+  #     - POSTGRES_DB=shade
+  #   volumes:
+  #     - shade-pg-data:/var/lib/postgresql/data
+
+volumes:
+  shade-data:
+  # shade-pg-data: