Case mismatch causes `web+spoolman:` barcodes to never trigger spool loading

The bug
The process_line() function in usb-qr-scanner-read.sh defines the prefix as uppercase:

SPOOLMAN_PREFIX="WEB+SPOOLMAN:S-"

However, the scanner outputs the scanned code in lowercase (e.g. web+spoolman:s-1). The comparison [[ "$line" == "$SPOOLMAN_PREFIX"* ]] never matches, so post_next_spool_id is never called and no spool is loaded.

To Reproduce

1. Generate a spoolman barcode (e.g. web+spoolman:s-1)
2. Scan it with the USB scanner
3. Service logs show Scanned code: web+spoolman:s-1 but Magic code Scanned is never printed and no gcode is sent to Moonraker

Expected behavior
Scanning a web+spoolman:s-N barcode should call SET_NEXT_SPOOL_ID SPOOL_ID=N via Moonraker.

Fix
Convert the scanned line to uppercase before comparison so the match is case-insensitive:

process_line() {
    local line="$1"
    local line_upper="${line^^}"
    if [[ "$line_upper" == "WEB+SPOOLMAN:S-"* ]]; then
        echo "Magic code Scanned"
        SPOOL_ID="${line_upper#WEB+SPOOLMAN:S-}"
        post_next_spool_id "${SPOOL_ID}"
    elif [[ "$line" == "http"* ]]; then
        echo "URL Scanned"
        SPOOL_ID=`echo $line | cut -d'/' -f6`
        post_next_spool_id "${SPOOL_ID}"
    fi
}

Environment

• Scanner: MINJCODE MJ2818A
• AFC / Box Turtle MMU
• Moonraker + Klipper on RatRig running Kalico
• OS: debian

Inspect process_line() in usb-qr-scanner-read.sh, starting with its prefix comparison and the post_next_spool_id call. Done means a lowercase web+spoolman:s-N scan is recognized and sends SPOOL_ID=N to Moonraker without changing the existing URL handling.