feat(app): Home, the Library and the studyset sheets laid out as before

Home: plain cards on the surface, 16 dp apart, the goal first and the
Pomodoro timer after it in a new dashboard. The streak chip sits centred
in the app bar, and its sheet shows the days inside a big flame and the
week as marks over the weekdays' initials, with a word on today in a box.
The week names its day as "Thursday, Oct 8" and its days carry no
tooltip. The heatmap scrolls its weekdays with the weeks, outlines the
days to come, and names a day's activities with its date. The goal card
has a ring of 5 dp, a check once met and a pencil, and its sheet saves
across its width with Remove goal below. Arranging puts an eye on each
widget's corner and lifts the one picked up, with a tap the hand feels;
with every widget hidden, Customise brings arranging back. The stepper
moves to core, where the goal's sheet takes it too.

Library: the counts line includes files (PDFs); Refresh in the app bar
and pulling the list down sync now; a list that can't be read offers
Retry, which reads it again; the star keeps its square corners.

Studyset sheet: "Title *", the secondary title explained behind a
question mark, Inherit as a box beside the colour, and the description
in up to three lines with a chevron. Move sheet: round marks, the
studyset itself marked as current, the top level only while it is
inside another, archived studysets last under their heading, the
destination named in the footer, and a new studyset to move into, made
only once the move is.

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

@@ -34,7 +34,7 @@
   "studysetSheetSave": "Save",
   "studysetSheetTitleLabel": "Title",
   "studysetSheetSecondaryLabel": "Secondary title",
-  "studysetSheetSecondaryHelper": "Shown as a small label above the title.",
+  "studysetSheetSecondaryHelper": "Shown as a small label above the title on cards and the studyset's header. Paths use it to label tiers (Challenge, Milestone, Lesson).",
   "studysetSheetColor": "Colour",
   "studysetSheetDiscardTitle": "Discard changes?",
   "studysetSheetDiscardMessage": "You have unsaved changes to this studyset. Discard them and close the form?",
@@ -49,6 +49,10 @@
   "@studysetCountFlashcards": {"placeholders": {"count": {"type": "int"}}},
   "studysetCountNotes": "{count, plural, =1{1 note} other{{count} notes}}",
   "@studysetCountNotes": {"placeholders": {"count": {"type": "int"}}},
+  "studysetCountFiles": "{count, plural, =1{1 file} other{{count} files}}",
+  "@studysetCountFiles": {"placeholders": {"count": {"type": "int"}}},
+  "libraryRefresh": "Refresh",
+  "libraryRetry": "Retry",
   "studysetNoContent": "No content yet",
   "studysetActionReview": "Review",
   "studysetActionStudy": "Study",
@@ -257,19 +261,27 @@
   "studysetDragToReorder": "Drag to reorder",
   "studysetMoveTitle": "Move studyset to",
   "studysetMoveTopLevel": "Top level",
-  "studysetMoveCurrent": "Where it is now",
+  "studysetMoveCurrent": "(current)",
+  "studysetMoveTopLevelRow": "Top level (no parent)",
+  "studysetMoveArchived": "Archived",
+  "studysetMoveNew": "New studyset",
+  "studysetMoveSelectDestination": "Select a destination",
+  "studysetMoveDestination": "Destination: {name}",
+  "@studysetMoveDestination": {"placeholders": {"name": {"type": "String"}}},
   "studysetMoveConfirm": "Move",
-  "studysetMoveShowInside": "Show what is inside",
-  "studysetMoveHideInside": "Hide what is inside",
-  "studysetMoved": "Moved to {destination}.",
-  "@studysetMoved": {"placeholders": {"destination": {"type": "String"}}},
+  "studysetMoveShowInside": "Show sub-studysets",
+  "studysetMoveHideInside": "Hide sub-studysets",
+  "studysetMoved": "Moved \"{title}\" to {destination}.",
+  "@studysetMoved": {"placeholders": {"title": {"type": "String"}, "destination": {"type": "String"}}},
   "studysetReadMore": "Read more",
   "studysetDescriptionTitle": "Description",
   "studysetDescriptionEditTitle": "Edit description",
   "richTextSave": "Save",
   "studysetSheetDescription": "Description",
-  "studysetSheetDescriptionAdd": "Add a description",
-  "studysetSheetInheritColor": "Same colour as the studyset it is in",
+  "studysetSheetDescriptionAdd": "Tap to add a description",
+  "studysetSheetDescriptionAdded": "Description added — tap to edit",
+  "studysetSheetInheritColor": "Inherit",
+  "fieldRequired": "required",
 
   "exploreTitle": "Explore",
   "exploreEmpty": "Studysets that others share will appear here.",
@@ -677,8 +689,9 @@
   "homeHideWidget": "Hide {label}",
   "@homeHideWidget": {"placeholders": {"label": {"type": "String"}}},
   "homeAllHidden": "All widgets are hidden",
-  "homeAllHiddenHint": "Long-press here to bring some back.",
-  "homeWidgetGoal": "Study goal",
+  "homeAllHiddenBody": "Bring some back to fill your dashboard.",
+  "homeCustomise": "Customise",
+  "homeWidgetGoal": "Daily goal",
   "homeWidgetWeek": "Week overview",
   "homeWidgetActivity": "Activity heatmap",
   "homeActivityTitle": "Your activity",
@@ -713,13 +726,11 @@
   "weekPreviousDay": "Previous day",
   "weekNextDay": "Next day",
   "weekRestDay": "Rest day",
-  "weekDueCount": "{count, plural, =1{1 card due} other{{count} cards due}}",
-  "@weekDueCount": {"placeholders": {"count": {"type": "int"}}},
   "heatmapLess": "Less",
   "heatmapMore": "More",
   "heatmapTotal": "{count, plural, =1{1 activity in the last year} other{{count} activities in the last year}}",
   "@heatmapTotal": {"placeholders": {"count": {"type": "int"}}},
-  "heatmapDay": "{count, plural, =0{Nothing} =1{1 activity} other{{count} activities}} · {date}",
+  "heatmapDay": "{count, plural, =1{1 activity} other{{count} activities}} · {date}",
   "@heatmapDay": {"placeholders": {"count": {"type": "int"}, "date": {"type": "String"}}},
 
   "commonCancel": "Cancel",
@@ -1006,7 +1017,7 @@
   "readerCaptureFailed": "The page couldn't be drawn. Try again once it has loaded.",
   "readerScreenshotSaved": "Screenshot saved",
   "imageOpenPdfPage": "Open the PDF at this page",
-  "homeWidgetDeadlines": "Reading deadlines",
+  "homeWidgetDeadlines": "PDF reading deadlines",
   "deadlinesTitle": "Reading deadlines",
   "deadlinesCurrent": "Current",
   "deadlinesUpcoming": "Upcoming",