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>

housekeeping/db-backup--swarm.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# ==============================================================================
+# MongoDB Offline Volume Backup Script (Docker Swarm)
+# ==============================================================================
+#
+# PURPOSE:
+#   Creates an offline backup of the complete mongo-volume directory.
+#   The MongoDB service is scaled down during the backup to ensure consistency.
+#
+# WHEN TO USE:
+#   - For Docker Swarm deployments (not standalone Docker)
+#   - When you need a complete volume backup (entire MongoDB data directory)
+#   - For disaster recovery scenarios
+#   - When consistency is critical and downtime is acceptable
+#
+# BACKUP TYPE:
+#   - Offline (cold) backup - DB service is scaled to 0 during backup
+#   - Volume-level backup - entire mongo-volume directory
+#   - Creates compressed tarball (.tar.gz) of the volume
+#
+# OUTPUT:
+#   - Backup files stored in: ./mongo-backup/
+#   - Filename format: mongo-volume-backup-YYYY-MM-DD-HH-MM.tar.gz
+#   - Automatic rotation: keeps newest 7 backups (configurable via KEEP env var)
+#
+# USAGE:
+#   ./db-backup--swarm.sh
+#   KEEP=10 ./db-backup--swarm.sh  # Keep 10 backups instead of 7
+#
+# NOTE:
+#   The MongoDB service will be scaled down to 0 and then back up to 1.
+#   Expect brief downtime during the backup process.
+#
+# ==============================================================================
+
+# Configuration
+MONGO_SERVICE="utility-bills-tracker_mongo"
+
+# scale down mongo service while we copy its volume
+docker service scale "$MONGO_SERVICE"=0
+
+# timestamp for filename
+TIMESTAMP=$(date +"%Y-%m-%d-%H-%M")
+
+# backup directory and retention (can be overridden via env)
+BACKUP_DIR="${BACKUP_DIR:-mongo-backup}"
+KEEP="${KEEP:-7}"
+
+mkdir -p "$BACKUP_DIR"
+
+BACKUP_FILE="$BACKUP_DIR/mongo-volume-backup-$TIMESTAMP.tar.gz"
+
+sudo tar -czvpf "$BACKUP_FILE" mongo-volume
+
+# rotate old backups: keep only the newest $KEEP files
+if [ "$KEEP" -gt 0 ]; then
+  # gather files sorted newest-first
+  mapfile -t files < <(ls -1t "$BACKUP_DIR"/mongo-volume-backup-*.tar.gz 2>/dev/null || true)
+  if [ "${#files[@]}" -gt "$KEEP" ]; then
+    for f in "${files[@]:$KEEP}"; do
+      echo "Removing old backup: $f"
+      rm -f -- "$f"
+    done
+  fi
+fi
+
+# bring mongo service back up
+docker service scale "$MONGO_SERVICE"=1