Fix USB backup permission issues

**Problem:**
- USB drives mounted as root were not writable by regular user
- Caused "Permission denied" errors on backup
- Required running application as root (not secure)

**Solution:**
- Better permission error messages with fix suggestions
- Try to create backup directory first (more flexible)
- Show helpful error: "run sudo chown -R \$USER /media/usb0"

**USB Setup Script (setup_usb.sh):**
- Interactive USB drive mounting
- Automatically detects USB devices
- Mounts with user ownership (uid/gid)
- Tests write permissions
- Shows free space
- Offers to add to /etc/fstab
- Color-coded output

**Documentation Updates:**
- Added 3 methods for mounting with permissions
- Recommended method: mount with uid/gid options
- Added fstab auto-mount example
- Added quick setup script example
- Clear instructions for each method

**Usage:**
```bash
# Easiest method
sudo ./setup_usb.sh

# Or manual mounting
sudo mount -o uid=$(id -u),gid=$(id -g) /dev/sda1 /media/usb0

# Or fix existing mount
sudo chown -R $USER /media/usb0
```

**Security:**
- No need to run wedding phone as root
- User-owned USB mount points
- Proper permission checking
- Clear error messages

**Web Interface:**
- Shows helpful permission error messages
- Includes fix command in error text
- Better UX for permission issues

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

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

README.md

@@ -325,18 +325,70 @@ Automatically backup all recordings and greeting files to USB drives:
 6. Corrupted copies deleted automatically
 7. Success/failure logged to console
 
-**Mount USB Drives:**
+**Mount USB Drives with Proper Permissions:**
+
+**Automated Setup (Easiest):**
 ```bash
+# Run the USB setup script
+sudo ./setup_usb.sh
+```
+This interactive script will:
+- Detect your USB devices
+- Mount them with proper user permissions
+- Test write access
+- Optionally add to /etc/fstab for auto-mounting
+
+**Option 1: Mount with user permissions (Recommended)**
+```bash
+# Find your USB device
+lsblk
+
+# Create mount point
+sudo mkdir -p /media/usb0
+
+# Mount with user ownership (replace $USER with your username if needed)
+sudo mount -o uid=$(id -u),gid=$(id -g) /dev/sda1 /media/usb0
+
+# Verify it's writable
+touch /media/usb0/test.txt && rm /media/usb0/test.txt
+```
+
+**Option 2: Auto-mount in /etc/fstab with user permissions**
+```bash
+# Get USB UUID
+sudo blkid /dev/sda1
+
+# Edit fstab
+sudo nano /etc/fstab
+
+# Add line (replace UUID and username):
+UUID=XXXX-XXXX  /media/usb0  vfat  defaults,nofail,uid=1000,gid=1000  0  0
+# Note: uid=1000 is usually the first user, check with: id -u
+```
+
+**Option 3: Change ownership after mounting**
+```bash
+# Mount normally
+sudo mount /dev/sda1 /media/usb0
+
+# Change ownership (replace with your username)
+sudo chown -R $USER:$USER /media/usb0
+```
+
+**Quick Setup Script:**
+```bash
+#!/bin/bash
+# setup_usb.sh - Mount USB drives with proper permissions
+
 # Create mount points
 sudo mkdir -p /media/usb0 /media/usb1
 
-# Auto-mount in /etc/fstab (example)
-UUID=XXXX-XXXX  /media/usb0  vfat  defaults,nofail  0  0
-UUID=YYYY-YYYY  /media/usb1  vfat  defaults,nofail  0  0
+# Mount USB drives with user ownership
+sudo mount -o uid=$(id -u),gid=$(id -g) /dev/sda1 /media/usb0
+sudo mount -o uid=$(id -u),gid=$(id -g) /dev/sdb1 /media/usb1
 
-# Or mount manually
-sudo mount /dev/sda1 /media/usb0
-sudo mount /dev/sdb1 /media/usb1
+echo "USB drives mounted!"
+ls -la /media/usb0 /media/usb1
 ```
 
 ## File Structure
@@ -347,6 +399,7 @@ wedding-phone/
 ├── test_complete.py           # Audio testing script
 ├── configure_hifiberry.sh     # HiFiBerry setup script
 ├── install_service.sh         # Systemd service installer
+├── setup_usb.sh               # USB drive setup with permissions
 ├── wedding-phone.service      # Systemd service file
 ├── Makefile                   # Make commands for easy running
 ├── config.example.json       # Example configuration (copy to config.json)