fix(app): the dictionary adds each word once, says when it can't, and Look up tags hold

- A word tapped twice, or added while a level is being added, makes one
  card: adds run one at a time, and the word counts as in the studyset
  at once. The adder reads the studyset's cards once rather than for
  every word.
- Adding that fails says so, and a level shows "Making the cards…" once
  its words have come.
- Finding a studyset's dictionary tells finding, none and unreachable
  apart: the dictionary screen says there is none or offers Retry, and
  an instance unreachable at start is asked again once a sync goes
  through (Look up and From the dictionary appear then).
- Look up's tags wait on the card by name and are made when it is saved:
  leaving the card at once no longer saves it untagged, a word replaced
  leaves no tag behind, and a new word replaces any level or word class
  on the card, pinned ones too. Look up marks words already made into
  cards of the studyset.
- The tag picker's Create keeps the case typed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMm7usAo6q9ZZRoPkWjoxi
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/l10n/app_en.arb

@@ -543,6 +543,9 @@
   "@dictionaryNothingFound": {"placeholders": {"query": {"type": "String"}}},
   "dictionaryUnreachable": "The dictionary can't be reached right now.",
   "dictionaryRetry": "Retry",
+  "dictionaryAddFailed": "Couldn't add the words. Try again.",
+  "dictionaryMakingCards": "Making the cards…",
+  "dictionaryNone": "This studyset's language has no dictionary on this instance.",
   "dictionaryAdd": "Add",
   "dictionaryInStudyset": "In this studyset",
   "dictionaryAdded": "Added “{word}”.",