feat(app): tag, edit, delete and swipe cards while studying, with tidier session sheets

- Above every studied card (but a matching one): the PDF it came from,
  its tags on one line ("+2 tags" for the rest) or "Add tags", and a
  menu to tag, edit or delete it; the session follows (an edited card
  shows as saved, a deleted one leaves the round).
- On phones, a front/back or vocabulary card swiped right is rated
  Good, left Bad; it tilts over the colour it heads for, and springs
  back when let go early.
- The session's settings: "Settings", a 48 dp Save that warns mid-round
  ("Heads up!"), steppers in an outlined box ("20 / day", "5 / 50"),
  the order in an outlined dropdown, the chosen tags with the rest
  behind "Filter by tags" / "+3 more".
- A studyset's study options: Save above Reset to defaults, the
  description small, reviews a day in steps of 25.
- One stepper look everywhere (study, Pomodoro profiles), its buttons
  "Decrease" and "Increase".

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

@@ -366,13 +366,20 @@
   "@tagDeleted": {"placeholders": {"name": {"type": "String"}}},
   "studySettingsTitle": "Session settings",
   "studySettingsFilterByTags": "Filter by tags",
-  "studySettingsFilterHint": "Study only the flashcards with any of the tags chosen.",
-  "studySettingsNoTags": "No tags yet. Add tags to your flashcards to filter them here.",
+  "studySettingsNoTags": "No content tags yet. Add tags to your cards to filter them here.",
   "studySettingsReset": "Reset",
   "studySettingsSave": "Save",
+  "studySettingsHeadsUpTitle": "Heads up!",
+  "studySettingsHeadsUpBody": "The changes you’ve made will reload the session, and you’ll lose your current progress.",
+  "studySettingsApplyChanges": "Apply changes",
+  "studySettingsPerDay": " / day",
+  "studySettingsMoreTags": "+{count} more",
+  "@studySettingsMoreTags": {"placeholders": {"count": {"type": "int"}}},
   "cardTagsLabel": "Tags",
   "cardTagsAdd": "Add tags",
   "cardTagsEdit": "Edit tags",
+  "tagChipsOverflow": "+{count, plural, =1{1 tag} other{{count} tags}}",
+  "@tagChipsOverflow": {"placeholders": {"count": {"type": "int"}}},
   "cardFilterTooltip": "Filter",
   "cardFilterTitle": "Filter",
   "cardFilterTag": "Tag",
@@ -560,7 +567,6 @@
   "studyOptionsTitle": "Study options",
   "studyOptionsDescription": "How many cards this studyset brings a day, and which come first, on every device. The studysets inside it keep their own.",
   "studyOptionsReviewsPerDay": "Reviews per day",
-  "studyOptionsReviewsPerDayHint": "Cards in their learning steps come anyway.",
   "studyOptionsOrder": "Order",
   "studyOptionsReviewsFirst": "Reviews first",
   "studyOptionsMixed": "Mixed",
@@ -576,8 +582,8 @@
   "studySortOldestFirst": "Oldest first",
   "studySortRandom": "Random",
   "studySortNewestFirst": "Newest first",
-  "studyFewer": "Fewer",
-  "studyMore": "More",
+  "studyFewer": "Decrease",
+  "studyMore": "Increase",
 
   "studysetMenuReset": "Reset progress",
   "studysetResetTitle": "Reset progress?",