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/BillDeleteForm.tsx

@@ -0,0 +1,71 @@
+"use client";
+
+import { FC, ReactNode, useState } from "react";
+import { Bill, BillingLocation } from "../lib/db-types";
+import { useFormState } from "react-dom";
+import { Main } from "./Main";
+import { deleteBillById } from "../lib/actions/billActions";
+import Link from "next/link";
+import { useTranslations } from "next-intl";
+
+export interface BillDeleteFormProps {
+    bill: Bill,
+    location: BillingLocation
+}
+
+export const BillDeleteForm:FC<BillDeleteFormProps> = ({ bill, location }) => {
+
+    const { year, month } = location.yearMonth;
+    const handleAction = deleteBillById.bind(null, location._id, bill._id, year, month);
+    const [ state, dispatch ] = useFormState(handleAction, null);
+    const t = useTranslations("bill-delete-form");
+    const [deleteInSubsequentMonths, setDeleteInSubsequentMonths] = useState(false);
+
+    return(
+        <div className="card card-compact card-bordered min-w-[20em] max-w-[90em] bg-base-100 shadow-s my-1">
+            <div className="card-body">
+                <form action={dispatch}>
+                    <p className="py-6 px-6">
+                    {
+                        t.rich("text", {
+                            bill_name:bill.name,
+                            location_name:location.name,
+                            strong: (chunks:ReactNode) => <strong>{chunks}</strong>,
+                        })
+                    }
+                    </p>
+                    
+                    <div className="form-control">
+                        <label className="label cursor-pointer justify-center gap-4">
+                            <span className="label-text">{t("delete-in-subsequent-months")}</span> 
+                            <input 
+                                type="checkbox" 
+                                name="deleteInSubsequentMonths" 
+                                className="toggle toggle-error"
+                                checked={deleteInSubsequentMonths}
+                                onChange={(e) => setDeleteInSubsequentMonths(e.target.checked)}
+                            />
+                        </label>
+                    </div>
+                    
+                    {deleteInSubsequentMonths && (
+                        <div className="border-l-4 border-error bg-error/10 p-4 mt-4 rounded-r max-w-[24rem] mx-auto">
+                            <div className="flex items-start gap-3">
+                                <span className="text-xl flex-shrink-0">⚠️</span>
+                                <div className="flex-1 min-w-0">
+                                    <h3 className="font-bold text-error break-words">{t("warning-title")}</h3>
+                                    <div className="text-sm text-error/80 break-words">{t("warning-message")}</div>
+                                </div>
+                            </div>
+                        </div>
+                    )}
+                    
+                    <div className="pt-4 text-center">
+                        <button className="btn btn-primary w-[5.5em]">{t("confirm-button")}</button>
+                        <Link className="btn btn-neutral w-[5.5em] ml-3" href={`/home/bill/${location._id}-${bill._id}/edit/`}>{t("cancel-button")}</Link>
+                    </div>
+                </form>
+            </div>
+        </div>
+    )
+}