Feature Request: "SMB share" one way Sync to -> "USB Drive"

# Feature Request: One-Way SMB Sync to USB Drive

## Summary
Add a simple one-way SMB sync feature that allows Panda Touch to download files from a configured SMB network share directly to the USB flash drive connected to the device.

## Problem
Current workflow requires:
1. Exporting/saving the sliced file on a PC or to a USB
2. Physically moving the USB drive to Panda Touch

This manual process is time-consuming and inconvenient.

## Proposed Solution
Allow Panda Touch to:
- Connect to a configured SMB network share
- Sync (download) files from that share directly to the connected USB drive
- Operate as a one-way sync only (SMB → USB)

## Benefits
- Eliminates manual USB transfers between PC and Panda Touch
- Streamlines the printing workflow
- Allows the network share to act as a central file repository and backup location

## Suggested Scope
- One-way sync only (no upload from USB to SMB)
- Configurable SMB settings (IP address, share path, username/password)
- Manual "Sync Now" button

Thank you for considering this feature.

No files, tests, or entry points are identified. Start by mapping Panda Touch's existing network configuration and USB file-transfer paths, then clarify SMB library, credential handling, conflict behavior, and completion criteria before implementation.

Written by the indexing model from the issue text.