feat(kanban): deadlines en cards (context menu, badges, calendario, history)

- migration 009 + columna deadline TEXT en cards
- backend: CardPatch.HasDeadline, eventos deadline_set/deadline_cleared
- KanbanCard: menu derecho con DatePicker, badge countdown con colores por ratio (azul>=50%, amarillo<50%, rojo<10%, red.9 overdue)
- App.tsx: filtro "Con deadline", handleSetCardDeadline optimista, jump-to-card + highlight
- CalendarView: popover por dia con seq_num + titulo, click navega a card en tablero
- HistoryModal: render eventos deadline_set/deadline_cleared
- .gitignore: *.log

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/tsconfig.json

@@ -17,8 +17,8 @@
     "noFallthroughCasesInSwitch": true,
     "baseUrl": ".",
     "paths": {
-      "@fn_library": ["../../../frontend/functions/ui"],
-      "@fn_library/*": ["../../../frontend/functions/ui/*"]
+      "@fn_library": ["../../../frontend/functions"],
+      "@fn_library/*": ["../../../frontend/functions/*"]
     }
   },
   "include": ["src"]