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/[locale]/home/bill/[id]/delete/not-found.tsx

@@ -0,0 +1,6 @@
+import { NotFoundPage } from '@/app/ui/NotFoundPage';
+ 
+const BillNotFound = () =>
+<NotFoundPage title="404 Bill Not Found" description="Could not find the requested Bill." />;
+
+export default BillNotFound;

web-app/app/[locale]/home/bill/[id]/delete/page.tsx

@@ -0,0 +1,20 @@
+import { notFound } from 'next/navigation';
+import { BillDeleteForm } from '@/app/ui/BillDeleteForm';
+import { fetchBillById } from '@/app/lib/actions/billActions';
+import { Main } from '@/app/ui/Main';
+
+export default async function Page({ params:{ id } }: { params: { id:string } }) {
+    const [locationID, billID] = id.split('-');
+
+    const [location, bill] = await fetchBillById(locationID, billID) ?? [];
+    
+    if (!location || !bill) {
+        return(notFound());
+    }
+
+    return (
+        <Main>
+            <BillDeleteForm location={location} bill={bill} />
+        </Main>
+    );
+}