feat(todo): a project laid out as a board, its columns its sections (ADR 0033, D17)

The Display's new Layout picks List or Board. The board has a column
for the tasks in no section, then one a section with its menu, each
task a card and each column ending with Add task, a last column adding
a section; grouped otherwise, a column a group. Narrower than a medium
width it pages one column at a time with dots below; from it on the
columns stand side by side. Cards drag within and between columns as
rows do (D16), every scrollable they are in scrolling at its edges.

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

@@ -608,5 +608,21 @@
   "groupNoLabel": "No label",
   "@groupNoLabel": {
     "description": "A project's group of tasks without a label (ADR 0033, D17)."
+  },
+  "layoutTitle": "Layout",
+  "@layoutTitle": {
+    "description": "A project's layout in its Display, and its board's columns (ADR 0033, D17)."
+  },
+  "layoutList": "List",
+  "@layoutList": {
+    "description": "A project's layout in its Display, and its board's columns (ADR 0033, D17)."
+  },
+  "layoutBoard": "Board",
+  "@layoutBoard": {
+    "description": "A project's layout in its Display, and its board's columns (ADR 0033, D17)."
+  },
+  "boardNoSection": "(No section)",
+  "@boardNoSection": {
+    "description": "A project's layout in its Display, and its board's columns (ADR 0033, D17)."
   }
 }