feat(jellyfin): any stretch of a line's characters chosen by hand

The cut takes the longest word and knows no grammar, so 今日は reads as
こんにちは where it is 今日 and は. Any stretch of a line's characters can
now be chosen by hand: dragged across with a mouse, Shift+clicked from
the word or stretch chosen, or on a touch screen held on a character and
dragged on. It is looked up as one word, as it stands or as a form of
one, in one small request (the instance has the line's text already);
while it is chosen the line reads it as that word (きょう over 今日), and
what the dictionary lacks as one word is offered as a search on Jisho.

The line's words move into line_words.dart, out of the Watch screen.

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

halkyon_learn_flutter/lib/l10n/app_en.arb

@@ -2158,8 +2158,12 @@
   "@watchWordCount": {"placeholders": {"count": {"type": "int"}}},
   "watchAdd": "Add",
   "watchAdded": "{word} added",
+  "watchStretchNone": "{text} isn't in the dictionary as one word.",
+  "@watchStretchNone": {"placeholders": {"text": {"type": "String"}}},
+  "watchStretchFailed": "Couldn't look it up. Choose it again to try once more.",
+  "watchStretchJisho": "Search Jisho for it",
   "@watchAdded": {"placeholders": {"word": {"type": "String"}}},
-  "watchTapAWord": "Tap a word of the subtitles to look it up.",
+  "watchTapAWord": "Tap a word of the subtitles to look it up, or drag across characters to look up any part of a line (on a touch screen, hold first).",
   "watchFormOf": "A form of {word}",
   "@watchFormOf": {"placeholders": {"word": {"type": "String"}}},
   "watchFailed": "The video couldn't be played."