feat: add Docker support with single-port deployment

Add complete Docker configuration for containerized deployment:
- Multi-stage Dockerfile using official Bun runtime
- docker-compose.yml for single-port stack orchestration
- Host-mounted database volume with auto-initialization
- Custom database init script using bun:sqlite
- Entrypoint script for seamless database setup
- Environment configuration template
- Comprehensive DOCKER.md documentation

Key features:
- Single exposed port (3001) serving both API and frontend
- Database persists in ./data directory on host
- Auto-creates database from template on first startup
- Health checks for monitoring
- Architecture-agnostic (works on x86 and ARM64)

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

Dockerfile

@@ -0,0 +1,72 @@
+# Multi-stage Dockerfile for Quickawards
+# Uses official Bun runtime image
+
+# ============================================
+# Stage 1: Dependencies & Database Init
+# ============================================
+FROM oven/bun:1 AS builder
+
+WORKDIR /app
+
+# Install ALL dependencies (including devDependencies for drizzle-kit)
+COPY package.json bun.lock ./
+RUN bun install --frozen-lockfile
+
+# Copy source code (node_modules excluded by .dockerignore)
+COPY . .
+
+# Reinstall frontend dependencies to get correct platform binaries
+RUN cd src/frontend && bun install
+
+# Initialize database using custom script
+# This creates a fresh database with the correct schema using bun:sqlite
+RUN bun src/backend/scripts/init-db.js
+
+# Build frontend
+RUN bun run build
+
+# ============================================
+# Stage 2: Production Image
+# ============================================
+FROM oven/bun:1 AS production
+
+WORKDIR /app
+
+# Install production dependencies only
+COPY package.json bun.lock ./
+RUN bun install --frozen-lockfile --production
+
+# Copy backend source and schema files
+COPY src/backend ./src/backend
+COPY award-definitions ./award-definitions
+COPY drizzle.config.ts ./
+
+# Copy frontend build from builder stage
+COPY --from=builder /app/src/frontend/build ./src/frontend/build
+
+# Copy initialized database from builder (will be used as template)
+COPY --from=builder /app/src/backend/award.db /app/award.db.template
+
+# Copy drizzle migrations (if they exist)
+COPY --from=builder /app/drizzle ./drizzle
+
+# Create directory for database volume mount
+RUN mkdir -p /data
+
+# Copy entrypoint script
+COPY docker-entrypoint.sh /usr/local/bin/
+RUN chmod +x /usr/local/bin/docker-entrypoint.sh
+
+# Set environment variables
+ENV NODE_ENV=production \
+    PORT=3001 \
+    LOG_LEVEL=info
+
+# Expose the application port
+EXPOSE 3001
+
+# Use entrypoint script to handle database initialization
+ENTRYPOINT ["docker-entrypoint.sh"]
+
+# Start the backend server
+CMD ["bun", "run", "src/backend/index.js"]