Generalize PDF-to-JPEG conversion script

feat: accept PDF filename as input argument

- Allow PDF file to be specified on the command line
- Derive output JPEG name from input PDF basename
- Generate files using IMG_<pdf-name>.jpg naming convention
- Retain first-page conversion behavior
- Improve script reusability for multiple PDFs

pdf tools/pdf2img.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+# Convert the first page of a PDF to a JPEG image.
+# Usage: ./pdf_to_jpg.sh <file.pdf>
+
+set -euo pipefail
+
+if [[ $# -ne 1 ]]; then
+    echo "Usage: $0 <file.pdf>"
+    exit 1
+fi
+
+INPUT_PDF="$1"
+
+if [[ ! -f "$INPUT_PDF" ]]; then
+    echo "Error: '$INPUT_PDF' not found."
+    exit 1
+fi
+
+# Remove .pdf extension and prepend IMG_
+BASE_NAME="$(basename "$INPUT_PDF" .pdf)"
+OUTPUT_JPG="IMG_${BASE_NAME}.jpg"
+
+echo "Converting first page of '$INPUT_PDF' to '$OUTPUT_JPG'..."
+
+pdftoppm -f 1 -l 1 "$INPUT_PDF" | pnmtojpeg > "$OUTPUT_JPG"
+
+echo "Done: $OUTPUT_JPG created."