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/vite.config.ts

@@ -6,7 +6,7 @@ export default defineConfig({
   plugins: [react()],
   resolve: {
     alias: {
-      "@fn_library": path.resolve(__dirname, "../../../frontend/functions/ui"),
+      "@fn_library": path.resolve(__dirname, "../../../frontend/functions"),
     },
   },
   server: {
@@ -16,6 +16,7 @@ export default defineConfig({
     },
   },
   build: {
-    outDir: "dist",
+    outDir: "../backend/dist",
+    emptyOutDir: true,
   },
 });