library: add Quick Add page (scan an ISBN, the book is added)

A small standard-library Python service next to Koha:
- looks the code up via Z39.50 (yaz) then Open Library over HTTPS
- checks Koha for an existing copy (ISBN-10/13 and UPC/EAN aware)
- adds the record + an item with the next barcode via Koha's REST API
- scanner-friendly UI: auto-focus, audible feedback, duplicate card with
  'add another copy', manual entry when nothing is found, undo, and the
  barcode range to print labels for
Also: enable RESTBasicAuth, map 024$a to the ean column, wire the service,
port and credentials into compose/install.sh.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013wi3ZSot4XbUViwRFgLpRf

library/docker-compose.yml

@@ -43,6 +43,31 @@ services:
     volumes:
       - koha-data:/var/lib/koha
 
+  # Scan an ISBN -> the book is added (Z39.50 lookup, then Koha's REST API).
+  quickadd:
+    build:
+      context: ./quickadd
+    image: library-quickadd:local
+    container_name: library-quickadd
+    restart: unless-stopped
+    depends_on:
+      koha:
+        condition: service_started
+    environment:
+      TZ: ${TZ:-UTC}
+      KOHA_API: http://koha:8081/api/v1
+      ADMIN_USER: ${ADMIN_USER:-admin}
+      ADMIN_PASSWORD: ${ADMIN_PASSWORD}
+      KOHA_LIBRARY: HOME
+      OPAC_PORT: ${OPAC_PORT:-8080}
+      STAFF_PORT: ${STAFF_PORT:-8081}
+      QUICKADD_SOURCES: ${QUICKADD_SOURCES:-z3950:lx2.loc.gov:210/LCDB,openlibrary}
+    ports:
+      - "${QUICKADD_PORT:-8082}:8082"
+    volumes:
+      - quickadd-data:/data
+
 volumes:
   db-data:
   koha-data:
+  quickadd-data: