fix: replace print() with logging across harness package (#1282)

Replace all bare print() calls with proper logging using Python's
standard logging module across the deerflow harness package.

Changes across 8 files (16 print statements replaced):

- agents/middlewares/clarification_middleware.py: use logger.info/debug
- agents/middlewares/memory_middleware.py: use logger.debug
- agents/middlewares/thread_data_middleware.py: use logger.debug
- agents/middlewares/view_image_middleware.py: use logger.debug
- agents/memory/queue.py: use logger.info/debug/warning/error
- agents/lead_agent/prompt.py: use logger.error
- skills/loader.py: use logger.warning
- skills/parser.py: use logger.error

Each file follows the established codebase convention:
  import logging
  logger = logging.getLogger(__name__)

Log levels chosen based on message semantics:
- debug: routine operational details (directory creation, timer resets)
- info: significant state changes (memory queued, updates processed)
- warning: recoverable issues (config load failures, skipped updates)
- error: unexpected failures (parsing errors, memory update errors)

Note: client.py is intentionally excluded as it uses print() for
CLI output, which is the correct behavior for a command-line client.

Co-authored-by: moose-lab <moose-lab@users.noreply.github.com>

backend/packages/harness/deerflow/agents/middlewares/clarification_middleware.py

@@ -1,5 +1,6 @@
 """Middleware for intercepting clarification requests and presenting them to the user."""
 
+import logging
 from collections.abc import Callable
 from typing import override
 
@@ -10,6 +11,8 @@ from langgraph.graph import END
 from langgraph.prebuilt.tool_node import ToolCallRequest
 from langgraph.types import Command
 
+logger = logging.getLogger(__name__)
+
 
 class ClarificationMiddlewareState(AgentState):
     """Compatible with the `ThreadState` schema."""
@@ -101,8 +104,8 @@ class ClarificationMiddleware(AgentMiddleware[ClarificationMiddlewareState]):
         args = request.tool_call.get("args", {})
         question = args.get("question", "")
 
-        print("[ClarificationMiddleware] Intercepted clarification request")
-        print(f"[ClarificationMiddleware] Question: {question}")
+        logger.info("Intercepted clarification request")
+        logger.debug("Clarification question: %s", question)
 
         # Format the clarification message
         formatted_message = self._format_clarification_message(args)