fix: logging, warnings, and soft-delete consistency

- Fix duplicate logging in multi-worker mode with file lock for cleanup scheduler
- Add Pydantic V2 model_config to suppress protected_namespaces warning
- Suppress PaddlePaddle ccache warnings
- Fix admin.py using non-existent User.username (now uses email)
- Fix get_user_stats to exclude soft-deleted tasks from statistics
- Fix create_task to exclude soft-deleted tasks from user limit check
- Change LOG_LEVEL default to INFO

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

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

.env

@@ -112,5 +112,5 @@ TASK_QUEUE_TYPE=memory
 CORS_ORIGINS=http://localhost:5173,http://127.0.0.1:5173
 
 # ===== Logging Configuration =====
-LOG_LEVEL=DEBUG
+LOG_LEVEL=INFO
 LOG_FILE=./logs/app.log