library: one address - Add books inside the staff site, plus Find a book

- Apache in the Koha container serves Quick Add at /add/ on the staff site
  (KOHA_QUICKADD_URL); koha now starts after quickadd so the name resolves
- Quick Add: relative API paths so it works at / and /add/; Add books / Find a
  book tabs; search by title, author or ISBN showing each copy's shelf and status
  (/api/search); Manage and Public catalogue links
- staff home gets a 'Library tools' block (HTML customizations, how Koha 26.05
  stores it) linking to Add books
- installer, kiosk add-on and READMEs advertise one main address; the public
  catalogue stays on its own port (Koha gives public and staff sites the same URL
  shapes, so they cannot share one address)

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

menus/addon_library.sh

@@ -217,10 +217,10 @@ action_library_show_access() {
         ip="localhost"
         echo "(Network access is limited to this kiosk.)"
     fi
-    echo "  Catalogue (public search):  http://${ip}:$(library_env_get OPAC_PORT)/"
-    echo "  Staff interface:            http://${ip}:$(library_env_get STAFF_PORT)/"
-    echo "  Add books (scan ISBNs):     http://${ip}:$(library_env_get QUICKADD_PORT)/"
-    echo "  Login (staff and add books): ${user}  /  ${pass}"
+    echo "  Your library (sign in here):  http://${ip}:$(library_env_get STAFF_PORT)/"
+    echo "      Add books:                http://${ip}:$(library_env_get STAFF_PORT)/add/"
+    echo "  Public catalogue (kiosk):     http://${ip}:$(library_env_get OPAC_PORT)/"
+    echo "  Login: ${user}  /  ${pass}   (Add books asks once more with the same login)"
     echo
     echo "  Passwords live in $LIBRARY_DIR/.env (root only)."
     pause