Author leave on the calendar itself

Planning used to mean filling in a wish list on one tab, pressing a button to
see a suggestion, then pressing another to accept it — with nothing on screen
telling you whether a plan was active. Dragging a range on the calendar now
creates the period directly, clicking a band opens it for editing, and each
change is recomputed and saved in one step. A period repeats never or yearly,
matching what the planner can actually express.

Clicking a day edits that day: its funding type, which pins it so the planner
leaves it alone, and whether the day counts as worked or off. That switch used
to be a mode covering the whole grid, which is what made the calendar confusing.

The season presets move to a rail beside the grid. Picking one lets the planner
choose the placement, then jumps there and flashes it, rather than asking the
user to guess dates the engine already knows.

A sync that funds nothing now says so, naming the period and how many days it
fell short, instead of leaving the screen unchanged and looking broken.

frontend/src/i18n/en/calendar.ts

@@ -49,6 +49,10 @@ export const calendar = {
   'plannedDayModal.leaveTypeLabel': 'Leave Type',
   'plannedDayModal.newTitle': 'Plan a Day',
   'plannedDayModal.parentLabel': 'Parent',
+  'plannedDayModal.pinnedNotice': 'This day is pinned by you — the planner will not change it automatically.',
+  'plannedDayModal.dayStatusLabel': 'This day is:',
+  'plannedDayModal.workdayOption': 'Working day',
+  'plannedDayModal.dayOffOption': 'Day off',
   'plannedDayModal.rangeTitle': 'Plan {count} days',
   'plannedDayModal.saveButton': 'Save',
   'plannedDayModal.saveError': 'Failed to save planned day',
@@ -63,4 +67,44 @@ export const calendar = {
   'redDaysList.overrideFree': 'Exception: day off',
   'redDaysList.overrideWorking': 'Exception: working day',
   'redDaysList.prevWindow': 'Previous 4 years',
+
+  // §Task7 — the calendar becomes the plan: drag-select, period popover,
+  // preset rail, and the sync toast/undo.
+  'calendar.newPeriodName': 'New period',
+  'calendar.periodCreateError': 'Failed to create the period',
+  'calendar.syncError': 'Failed to sync the plan',
+  'calendar.syncingLabel': 'Syncing…',
+  'calendar.toastChangedDays': '{name}: {count} day(s) changed',
+  'calendar.toastGenericPeriod': 'The period',
+  'calendar.toastShortfallNone':
+    '{name} ({start}–{end}): none of the {weeksWished} week(s) requested could be funded — {shortfallDays} day(s) short',
+  'calendar.toastShortfallPartial':
+    '{name} ({start}–{end}): only {weeksFunded} of {weeksWished} week(s) funded — {shortfallDays} day(s) short',
+  'calendar.undoButton': 'Undo',
+  'calendar.undoError': 'Failed to undo the change',
+  'calendar.dismissToastAria': 'Dismiss the message',
+
+  'calendar.railHeading': 'Add leave',
+  'calendar.railHint': 'Click to add — the calendar jumps to wherever it fits best.',
+  'calendar.presetAddAria': 'Add {name}',
+
+  'calendar.periodPopoverTitle': 'Edit period',
+  'calendar.periodAdHocTitle': 'Period',
+  'calendar.periodAdHocNotice': 'This period is not linked to a saved wish.',
+  'calendar.periodNameLabel': 'Name',
+  'calendar.periodNameAria': "The period's name",
+  'calendar.periodStartLabel': 'Start date',
+  'calendar.periodEndLabel': 'End date',
+  'calendar.periodRepeatLabel': 'Repeat',
+  'calendar.periodRepeatNever': 'Never',
+  'calendar.periodRepeatYearly': 'Yearly',
+  'calendar.periodLastYearLabel': 'Last year',
+  'calendar.periodSaveButton': 'Save period',
+  'calendar.periodSavingButton': 'Saving…',
+  'calendar.periodDeleteButton': 'Delete period',
+  'calendar.periodDeletingButton': 'Deleting…',
+  'calendar.periodDeleteConfirm': 'Are you sure you want to delete this period?',
+  'calendar.periodDeleteAdHocButton': 'Delete these days',
+  'calendar.periodCancelButton': 'Cancel',
+  'calendar.periodCloseAria': 'Close',
 } as const