Fix #206: Resolve auto interface to actual interface name

- Engine.__init__ now detects actual interface when config has 'auto'
- Uses get_primary_interface() to find default route interface
- PacketCapture module updated to use detected interface with fallback
- Handles Pi Zero 2W (wlan0) and other non-eth0 systems

modules/passive/packet_capture.py

@@ -23,6 +23,7 @@ from pathlib import Path
 from typing import Optional
 
 from modules.base import BaseModule
+from utils.networking import get_primary_interface
 
 logger = logging.getLogger("bb.passive.packet_capture")
 
@@ -62,7 +63,7 @@ class PacketCapture(BaseModule):
         if self._running:
             return
 
-        iface = self.config.get("interface", self.DEFAULT_INTERFACE)
+        iface = self.config.get("interface") or get_primary_interface() or self.DEFAULT_INTERFACE
         snap_len = self.config.get("snap_length", self.DEFAULT_SNAP_LEN)
         rotation = self.config.get("rotation_minutes", 60) * 60
         if rotation <= 0: