chore: convert to Turborepo + npm workspaces monorepo

- Move React/Vite frontend to apps/web/ (@budgetwise/web)
- Add apps/appwrite/ (@budgetwise/appwrite) to source-control the
  Appwrite backend: declarative schema in appwrite.json (5 collections),
  CLI-based deploy.sh for containerized use, functions/ dir for future
  Appwrite Functions
- Add turbo.json for task orchestration (build, deploy, dev)
- Replace .gitlab-ci.yml with Woodpecker CI pipelines in .woodpecker/:
    web-production.yml  — push to main → build + rsync to prod
    web-staging.yml     — push to staging → build + rsync to staging
    web-preview.yml     — PR open → deploy to {pr}.{domain}; PR close → cleanup
    appwrite.yml        — schema changes in apps/appwrite/ → CLI deploy
- All secrets injected via Woodpecker CI (no committed .env files)

apps/web/src/lib/calculations.ts

@@ -0,0 +1,205 @@
+import type {
+  Income,
+  BalanceSheet,
+  Bucket,
+  Debt,
+  MonthlySnapshot,
+  BucketAllocation,
+  LoanAnalysis,
+  DebtRepaymentPlan,
+  InvestmentProjection,
+} from '../types';
+
+// ─── Income ───────────────────────────────────────────────────────────────────
+
+export function toMonthly(amount: number, frequency: 'monthly' | 'yearly'): number {
+  return frequency === 'yearly' ? amount / 12 : amount;
+}
+
+export function totalMonthlyIncome(incomes: Income[]): number {
+  return incomes.reduce((sum, i) => sum + toMonthly(i.amount, i.frequency), 0);
+}
+
+// ─── Buffer ───────────────────────────────────────────────────────────────────
+
+export function bufferAmount(sheet: BalanceSheet, monthlyIncome: number): number {
+  if (sheet.buffer_type === 'percent') {
+    return monthlyIncome * (sheet.buffer_value / 100);
+  }
+  return sheet.buffer_value;
+}
+
+// ─── Bucket allocations ───────────────────────────────────────────────────────
+
+export function bucketMonthlyAllocation(bucket: Bucket, monthlyIncome: number): number {
+  if (bucket.goal_amount <= 0) return 0;
+  let amount = bucket.goal_amount;
+  if (bucket.goal_type === 'percent') {
+    amount = monthlyIncome * (bucket.goal_amount / 100);
+  }
+  if (bucket.goal_frequency === 'yearly') {
+    amount = amount / 12;
+  }
+  return amount;
+}
+
+export function allBucketAllocations(
+  buckets: Bucket[],
+  monthlyIncome: number,
+): BucketAllocation[] {
+  return buckets.map((b) => ({
+    bucket: b,
+    monthlyAmount: bucketMonthlyAllocation(b, monthlyIncome),
+  }));
+}
+
+// ─── Debt ─────────────────────────────────────────────────────────────────────
+
+/**
+ * EMI formula: P * r * (1+r)^n / ((1+r)^n - 1)
+ * r = monthly interest rate, n = term in months
+ */
+export function calculateEMI(principal: number, annualRate: number, termMonths: number): number {
+  if (annualRate === 0) return principal / termMonths;
+  const r = annualRate / 100 / 12;
+  const emi = (principal * r * Math.pow(1 + r, termMonths)) / (Math.pow(1 + r, termMonths) - 1);
+  return emi;
+}
+
+export function totalDebtPayments(debts: Debt[]): number {
+  return debts.reduce((sum, d) => sum + d.monthly_payment, 0);
+}
+
+// ─── Monthly Snapshot ─────────────────────────────────────────────────────────
+
+export function buildMonthlySnapshot(
+  sheet: BalanceSheet | null,
+  incomes: Income[],
+  buckets: Bucket[],
+  debts: Debt[],
+): MonthlySnapshot {
+  const monthlyIncome = totalMonthlyIncome(incomes);
+  const buffer = sheet ? bufferAmount(sheet, monthlyIncome) : 0;
+  const allocations = allBucketAllocations(buckets, monthlyIncome);
+  const totalBucket = allocations.reduce((s, a) => s + a.monthlyAmount, 0);
+  const debtPayments = totalDebtPayments(debts);
+  const available = monthlyIncome - buffer - totalBucket - debtPayments;
+
+  return {
+    balanceSheet: sheet,
+    incomes,
+    totalMonthlyIncome: monthlyIncome,
+    bufferAmount: buffer,
+    bucketAllocations: allocations,
+    totalBucketAllocation: totalBucket,
+    debtPayments,
+    available,
+  };
+}
+
+// ─── Loan Calculator ──────────────────────────────────────────────────────────
+
+/**
+ * Given a monthly payment P, monthly rate r and term n, the max principal is:
+ * principal = P * (1 - (1+r)^-n) / r
+ */
+export function maxLoanPrincipal(
+  monthlyPayment: number,
+  annualRate: number,
+  termMonths: number,
+): number {
+  if (annualRate === 0) return monthlyPayment * termMonths;
+  const r = annualRate / 100 / 12;
+  return (monthlyPayment * (1 - Math.pow(1 + r, -termMonths))) / r;
+}
+
+export function analyzeLoan(
+  availableMonthly: number,
+  annualRate: number,
+  termMonths: number,
+  desiredPrincipal?: number,
+): LoanAnalysis {
+  const r = annualRate / 100 / 12;
+  const maxPrincipal = maxLoanPrincipal(availableMonthly, annualRate, termMonths);
+  const principalForCalc = desiredPrincipal ?? maxPrincipal;
+  const monthly = calculateEMI(principalForCalc, annualRate, termMonths);
+
+  return {
+    maxAffordablePrincipal: maxPrincipal,
+    monthlyPaymentForMax: availableMonthly,
+    availableForLoan: availableMonthly,
+    rateMonthly: r * 100,
+    termMonths,
+  };
+}
+
+// ─── Debt repayment plan (avalanche method) ───────────────────────────────────
+
+export function buildRepaymentPlan(
+  debts: Debt[],
+  extraMonthly: number,
+): DebtRepaymentPlan[] {
+  if (debts.length === 0) return [];
+
+  // Sort by highest interest rate first (avalanche)
+  const sorted = [...debts].sort((a, b) => b.interest_rate - a.interest_rate);
+  let remaining = extraMonthly;
+
+  return sorted.map((debt, idx) => {
+    const extra = idx === 0 ? remaining : 0; // put all extra on highest-rate debt
+    const r = debt.interest_rate / 100 / 12;
+    const payment = debt.monthly_payment + extra;
+    let balance = debt.remaining_balance;
+    let months = 0;
+    let totalInterest = 0;
+
+    while (balance > 0 && months < 600) {
+      const interest = balance * r;
+      totalInterest += interest;
+      const principal = Math.min(payment - interest, balance);
+      balance -= principal;
+      months++;
+      if (payment <= interest) {
+        months = 9999; // never paid off
+        break;
+      }
+    }
+
+    return {
+      debt,
+      suggestedExtra: extra,
+      monthsToPayoff: months,
+      totalInterest,
+    };
+  });
+}
+
+// ─── Investment projection ────────────────────────────────────────────────────
+
+export function projectInvestment(
+  principal: number,
+  annualReturnPercent: number,
+  years: number,
+): number {
+  const r = annualReturnPercent / 100;
+  return principal * Math.pow(1 + r, years);
+}
+
+export function buildInvestmentProjection(bucket: Bucket): InvestmentProjection {
+  const annual =
+    bucket.return_frequency === 'monthly'
+      ? bucket.return_percent * 12
+      : bucket.return_percent;
+
+  const monthly = bucket.return_frequency === 'monthly'
+    ? bucket.current_balance * (bucket.return_percent / 100)
+    : bucket.current_balance * (bucket.return_percent / 100 / 12);
+
+  return {
+    bucket,
+    monthlyReturn: monthly,
+    projectedValue1Y: projectInvestment(bucket.current_balance, annual, 1),
+    projectedValue5Y: projectInvestment(bucket.current_balance, annual, 5),
+    projectedValue10Y: projectInvestment(bucket.current_balance, annual, 10),
+  };
+}

apps/web/src/lib/utils.ts

@@ -0,0 +1,62 @@
+import { format, parseISO } from 'date-fns';
+
+export function formatCurrency(amount: number, currency = 'USD'): string {
+  return new Intl.NumberFormat('en-US', {
+    style: 'currency',
+    currency,
+    minimumFractionDigits: 2,
+    maximumFractionDigits: 2,
+  }).format(amount);
+}
+
+export function formatPercent(value: number, decimals = 1): string {
+  return `${value.toFixed(decimals)}%`;
+}
+
+export function formatDate(dateString: string): string {
+  try {
+    return format(parseISO(dateString), 'MMM d, yyyy');
+  } catch {
+    return dateString;
+  }
+}
+
+export function monthName(month: number): string {
+  return new Date(2000, month - 1, 1).toLocaleString('default', { month: 'long' });
+}
+
+export function currentMonthYear(): { month: number; year: number } {
+  const now = new Date();
+  return { month: now.getMonth() + 1, year: now.getFullYear() };
+}
+
+export function clsx(...classes: (string | boolean | undefined | null)[]): string {
+  return classes.filter(Boolean).join(' ');
+}
+
+export const BUCKET_COLORS = [
+  '#6366f1', // indigo
+  '#8b5cf6', // violet
+  '#ec4899', // pink
+  '#f59e0b', // amber
+  '#10b981', // emerald
+  '#3b82f6', // blue
+  '#ef4444', // red
+  '#14b8a6', // teal
+  '#f97316', // orange
+  '#84cc16', // lime
+];
+
+export function randomBucketColor(): string {
+  return BUCKET_COLORS[Math.floor(Math.random() * BUCKET_COLORS.length)];
+}
+
+export function monthsToReadable(months: number): string {
+  if (months >= 9999) return 'Never (payment too low)';
+  if (months >= 12) {
+    const y = Math.floor(months / 12);
+    const m = months % 12;
+    return m > 0 ? `${y}y ${m}m` : `${y} year${y > 1 ? 's' : ''}`;
+  }
+  return `${months} month${months !== 1 ? 's' : ''}`;
+}