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/Main.tsx

@@ -0,0 +1,25 @@
+import { FC } from "react";
+import { PageHeader } from "./PageHeader";
+import { PageFooter } from "./PageFooter";
+import { NextIntlClientProvider, useMessages } from "next-intl";
+
+export interface MainProps {
+    children: React.ReactNode;
+}
+
+export const Main:FC<MainProps> = ({ children }) => {
+
+    const message = useMessages();
+
+    return(
+        <NextIntlClientProvider messages={message}>
+            <main className="flex min-h-screen flex-col bg-base-300">
+                <PageHeader />
+                <div className="sm:mx-auto px-4">
+                    {children}
+                </div>
+                <PageFooter />
+            </main>
+        </NextIntlClientProvider>
+    );
+}