Feat: Upgrade Docker deployment with multi-stage build and Nginx integration

- Upgrade Dockerfile to Go 1.24 with multi-stage build (backend + frontend)
- Add TA-Lib installation for technical analysis support
- Integrate frontend build into main container image
- Add Nginx reverse proxy configuration for API routing
- Update docker-compose.yml to simplified single-container architecture
- Update .dockerignore to include web source for build
- Improve health checks and startup time handling

Benefits:
- One-click deployment with single Docker image
- Better resource utilization with multi-stage build
- Production-ready Nginx frontend serving
- Easier maintenance and deployment

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.dockerignore

@@ -40,8 +40,9 @@ coin_pool_cache/
 # Config files (should be mounted)
 config.json
 
-# Web directory (has its own Dockerfile)
-web/
+# Web build artifacts (but include source for multi-stage build)
+web/node_modules/
+web/dist/
 
 # Temporary files
 tmp/