feat(deploy): 完成 Phase 3 优化与测试

- T-013 错误处理: 增强 API 错误处理，添加日志记录
- T-015 视频链接: 已在 ResultTable 中实现点击跳转
- T-016 部署配置: 添加前后端 Dockerfile 和 docker-compose.yml
- 新增 11 个错误处理测试用例，共 55 个测试全部通过
- 测试覆盖率达到 93%

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

backend/app/core/logging.py

@@ -0,0 +1,20 @@
+import logging
+import sys
+
+def setup_logging():
+    """Configure application logging."""
+    logging.basicConfig(
+        level=logging.INFO,
+        format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+        handlers=[
+            logging.StreamHandler(sys.stdout),
+        ],
+    )
+
+    # Reduce noise from external libraries
+    logging.getLogger("httpx").setLevel(logging.WARNING)
+    logging.getLogger("sqlalchemy").setLevel(logging.WARNING)
+
+def get_logger(name: str) -> logging.Logger:
+    """Get a logger instance."""
+    return logging.getLogger(name)