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/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "housekeeping",
+  "version": "2.20.0",
+  "private": true,
+  "description": "Database backup and maintenance scripts",
+  "scripts": {
+    "backup:standalone": "./db-backup--standalone.sh",
+    "backup:swarm": "./db-backup--swarm.sh",
+    "dump:standalone": "./db-dump--standalone.sh",
+    "restore:standalone": "./db-restore-from-dump--standalone.sh",
+    "restore:swarm": "./db-restore-from-backup--swarm.sh"
+  }
+}