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>

.dockerignore

@@ -1,19 +1,18 @@
 # Dependencies
 node_modules
-bun.lockb
-*.log
+# Note: bun.lock is needed by Dockerfile for --frozen-lockfile
 
 # Environment
 .env
 .env.*
+!.env.example
 
-# Database
+# Database - will be in volume mount
 **/*.db
 **/*.db-shm
 **/*.db-wal
-award.db
 
-# Build outputs
+# Build outputs - built in container
 src/frontend/build/
 src/frontend/.svelte-kit/
 src/frontend/dist/
@@ -34,20 +33,29 @@ Thumbs.db
 .git/
 .gitignore
 
-# Documentation
-README.md
+# Documentation (keep docs in image but don't need in build context)
+# README.md
 docs/
 *.md
 
 # Logs
 logs/
 *.log
-
-# PM2
-ecosystem.config.js
-.pm2/
+backend.log
 
 # Tests
 *.test.js
 *.test.ts
 coverage/
+
+# Docker files
+Dockerfile
+docker-compose.yml
+.dockerignore
+
+# CI/CD
+.github/
+.gitlab-ci.yml
+
+# Data directory (for volume mount)
+data/