Extension: inject Send-to-Tablet next to the arrival reminder banner too

New injection point on bookings_view pages — NewBook's own 'This Booking
is due to Arrive today. Do you want to go to Check-In?' banner
(.newbook_message.plain), confirmed from a real sample 2026-09-01. Shares
the row-injection's button/panel logic rather than duplicating it;
makeSendButton/togglePanel now take a variant ('block' for the list row's
table cell, 'inline' for this banner's flowing text context). Booking ID
extraction differs per shape: the list row has a checkbox value, this
banner's Check In button only carries it inside its onclick attribute's
URL, no separate structured attribute.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/extension-src/manifest.json

@@ -19,7 +19,10 @@
 
   "content_scripts": [
     {
-      "matches": ["https://appeu.newbook.cloud/bookings_lists_checkin*"],
+      "matches": [
+        "https://appeu.newbook.cloud/bookings_lists_checkin*",
+        "https://appeu.newbook.cloud/bookings_view/*"
+      ],
       "js": ["content-script.js"],
       "run_at": "document_idle"
     }