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/lead_agent/prompt.py

@@ -1,8 +1,11 @@
+import logging
 from datetime import datetime
 
 from deerflow.config.agents_config import load_agent_soul
 from deerflow.skills import load_skills
 
+logger = logging.getLogger(__name__)
+
 
 def _build_subagent_section(max_concurrent: int) -> str:
     """Build the subagent system prompt section with dynamic concurrency limit.
@@ -364,7 +367,7 @@ def _get_memory_context(agent_name: str | None = None) -> str:
 </memory>
 """
     except Exception as e:
-        print(f"Failed to load memory context: {e}")
+        logger.error("Failed to load memory context: %s", e)
         return ""