feat: implement timezone-aware logging system

- Fix inconsistent timestamp formats in logs for easier troubleshooting
- All logging systems now respect Docker TZ environment variable (e.g., TZ=America/New_York)
- Add TimezoneAwareFormatter for Python's standard logging module
- Enhance _log function with robust timezone support and fallbacks
- Replace placeholder logging functions with centralized core.logging._log
- Support both zoneinfo (Python 3.9+) and pytz (older versions)
- Users now see consistent timezone formatting across all log outputs

nfoguard.py

@@ -12,6 +12,7 @@ import logging
 import logging.handlers
 from pathlib import Path
 from datetime import datetime, timezone, timedelta
+from zoneinfo import ZoneInfo
 from fastapi import FastAPI, HTTPException, BackgroundTasks, Request
 from pydantic import BaseModel
 from typing import Optional, Dict, Any, List, Set, Tuple
@@ -31,6 +32,37 @@ from clients.external_clients import ExternalClientManager
 # Configuration & Logging
 # ---------------------------
 
+class TimezoneAwareFormatter(logging.Formatter):
+    """Formatter that respects the container timezone"""
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.timezone = self._get_local_timezone()
+    
+    def _get_local_timezone(self):
+        """Get the local timezone, respecting TZ environment variable"""
+        tz_name = os.environ.get('TZ', 'UTC')
+        
+        try:
+            # Try zoneinfo first (Python 3.9+)
+            return ZoneInfo(tz_name)
+        except ImportError:
+            # Fallback for older Python versions
+            try:
+                import pytz
+                return pytz.timezone(tz_name)
+            except:
+                # Final fallback to UTC
+                return timezone.utc
+        except:
+            # If zone name is invalid, fallback to UTC
+            return timezone.utc
+    
+    def formatTime(self, record, datefmt=None):
+        dt = datetime.fromtimestamp(record.created, tz=self.timezone)
+        if datefmt:
+            return dt.strftime(datefmt)
+        return dt.isoformat(timespec='seconds')
+
 def _setup_file_logging():
     """Setup file logging for NFOGuard"""
     log_dir = Path("/app/data/logs")
@@ -43,9 +75,8 @@ def _setup_file_logging():
         log_dir / "nfoguard.log", maxBytes=50*1024*1024, backupCount=3
     )
     
-    formatter = logging.Formatter(
-        '[%(asctime)s] %(levelname)s: %(message)s',
-        datefmt='%Y-%m-%dT%H:%M:%S+00:00'
+    formatter = TimezoneAwareFormatter(
+        '[%(asctime)s] %(levelname)s: %(message)s'
     )
     file_handler.setFormatter(formatter)
     logger.addHandler(file_handler)