feat(todo): a project's Calendar as a month on wide windows (ADR 0033, D17)

From 720 pixels of the Calendar's own width on, a month grid in place
of the agenda: the month's weeks from the week's first day, the days
of the months beside it muted, each day with as many of its tasks as
fit and the rest counted, opening the day's tasks in a sheet; past
days with their overdue and done tasks. A task held and dropped on
another day moves there (moveTask), a day's free space tapped adds a
task on it, a line tapped opens its task.

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

apps/todo/halkyon_todo_flutter/lib/l10n/app_en.arb

@@ -734,5 +734,14 @@
         "type": "int"
       }
     }
+  },
+  "monthMore": "{count} more",
+  "@monthMore": {
+    "description": "A project's Calendar as a month on wide windows (ADR 0033, D17): a day's tasks that don't fit.",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
   }
 }