fix(publish): a release sends exactly the tag names the sheet showed (ADR 0019)

The final reading of 22 Oct found that the names were worked out again
after the sync that comes before publishing, so a link to a private tag
the instance merged in during that sync sent a name nobody saw going. The
sheet now hands what it showed to Publish, and the device refuses before
anything goes out when the names worked out then differ
(PublishProblem.tagNamesChanged), reading them again for the person to
look at.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/learn/halkyon_learn_flutter/lib/l10n/app_en.arb

@@ -2429,6 +2429,7 @@
 
   "publishPrivateRefused": "It's private: only your devices can read it. Make it non-private first, in its menu.",
   "publishTagNames": "Its tags couldn't all be named. Sync, then try again.",
+  "publishTagNamesChanged": "The tags that would go with it changed since they were shown. Look at them again, then publish.",
   "studysetMenuMakePrivate": "Make private",
   "studysetMenuMakeReadable": "Make non-private",
   "studysetPrivateTitle": "Make “{title}” private?",