refactor: convert repository to monorepo with npm workspaces

Restructured the repository into a monorepo to better organize application code
and maintenance scripts.

## Workspace Structure
- web-app: Next.js application (all app code moved from root)
- housekeeping: Database backup and maintenance scripts

## Key Changes
- Moved all application code to web-app/ using git mv
- Moved database scripts to housekeeping/ workspace
- Updated Dockerfile for monorepo build process
- Updated docker-compose files (volume paths: ./web-app/etc/hosts/)
- Updated .gitignore for workspace-level node_modules
- Updated documentation (README.md, CLAUDE.md, CHANGELOG.md)

## Migration Impact
- Root package.json now manages workspaces
- Build commands delegate to web-app workspace
- All file history preserved via git mv
- Docker build process updated for workspace structure

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

web-app/app/ui/PrintButton.tsx

@@ -0,0 +1,33 @@
+"use client";
+
+import { PrinterIcon } from '@heroicons/react/24/outline';
+import { useTranslations } from 'next-intl';
+import { YearMonth } from '../lib/db-types';
+
+export interface PrintButtonProps {
+  yearMonth: YearMonth;
+    className?: string;
+}
+
+export const PrintButton: React.FC<PrintButtonProps> = ({ yearMonth, className }) => {
+  const t = useTranslations("home-page.month-card");
+
+  const handlePrintClick = () => {
+    window.open(`/home/print/${yearMonth.year}/${yearMonth.month}`, '_blank');
+  };
+
+  return (
+    <div className={`card card-compact card-bordered bg-base-100 shadow-s my-1 ${className}`}>
+      <button 
+        className="card-body tooltip self-center cursor-pointer" 
+        onClick={handlePrintClick}
+        data-tip={t("print-codes-tooltip")}
+      >
+        <span className='flex self-center'>
+          <PrinterIcon className="h-[1em] w-[1em] cursor-pointer text-4xl" />
+          <span className="ml-1 self-center text-sm sm:text-xs text-left sm:w-[5.5em] leading-[1.3em]">{t("print-codes-label")}</span>
+        </span>
+      </button>
+    </div>
+  );
+};