fix(PICAN): align socket handling with PIEthernet patterns

- Sentinel: sock = 0 → sock = -1 (0 is stdin, valid fd)
- openDevice(): close socket on ioctl/bind failure (resource leak)
- openDevice(): set O_NONBLOCK via fcntl after socket()
- openDevice(): check setsockopt() return value
- closeDevice(): call shutdown() before close(), reset sock to -1
- readDevice() / writeDevice(): guard against sock == -1
- Add missing #include <fcntl.h>

libs/main/io_devices/pican.h

@@ -73,7 +73,7 @@ protected:
 
 private:
 	PRIVATE_DECLARATION(PIP_EXPORT)
-	int sock;
+	int sock = -1;
 	int can_id, readed_id;
 };