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/lib/formatStrings.ts

@@ -0,0 +1,42 @@
+export const formatCurrency = (amount: number, currencyCode?: string | null) => {
+    // format number with 2 decimal places and a thousand separator
+    // amount is in cents
+    const amountInUnits = amount / 100;
+
+    // Use Intl.NumberFormat for proper currency formatting
+    try {
+        return new Intl.NumberFormat('hr-HR', {
+            style: 'currency',
+            currency: currencyCode ?? "EUR",
+            minimumFractionDigits: 2,
+            maximumFractionDigits: 2,
+        }).format(amountInUnits);
+    } catch (e) {
+        // Fallback if invalid currency code
+        console.error(`Invalid currency code: ${currencyCode}`, e);
+    }
+}
+
+/**
+ * Formats an IBAN for display with proper spacing
+ * Format: XX12 XXXX XXXX XXXX XXXX XX
+ * First group: 2 letters (country) + 2 digits (check) = 4 chars
+ * Following groups: 4 characters each
+ * Last group: can be less than 4 characters
+ * @param iban - IBAN string without spaces
+ * @returns Formatted IBAN with spaces
+ */
+export const formatIban = (iban: string | null | undefined): string => {
+    if (!iban) return "";
+
+    // Remove any existing spaces
+    const cleaned = iban.replace(/\s/g, '');
+
+    // Split into groups: first 4 chars, then groups of 4
+    const groups: string[] = [];
+    for (let i = 0; i < cleaned.length; i += 4) {
+        groups.push(cleaned.slice(i, i + 4));
+    }
+
+    return groups.join(' ');
+}