feat: initial BudgetWise budgeting app with Appwrite sync

Full-stack PWA budgeting app installable on Android via Chrome.

Features implemented:
- Monthly balance sheet: income sources (monthly/yearly), buffer (fixed $ or % of income)
- Buckets: regular, savings-goal, and investment types with custom goals
  (amount or % of income, monthly or yearly schedule)
- Debt tracker: manual or auto-EMI (amortization formula), interest rate,
  remaining balance tracking, avalanche-method repayment suggestions
- Loan calculator: max affordable principal and EMI checker based on
  remaining income after all expenses
- Investment projections: compound interest at monthly/yearly rate,
  1/5/10-year projections per bucket
- Deposit / withdraw transactions per bucket with balance history
- Appwrite self-hosted backend: auth, 5 collections (balance_sheets,
  incomes, buckets, debts, transactions)
- scripts/setup-appwrite.cjs: one-command DB setup via node-appwrite
- PWA manifest + service worker (vite-plugin-pwa) for Android install
- Dark mobile-first UI with TailwindCSS, Zustand state, React Router v6

https://claude.ai/code/session_01Ny2EMaZYvzk5SSVDAPgxpP

.env.example

@@ -0,0 +1,9 @@
+# Appwrite Configuration
+# Copy this to .env and fill in your self-hosted Appwrite details
+
+VITE_APPWRITE_ENDPOINT=https://your-appwrite-instance.com/v1
+VITE_APPWRITE_PROJECT_ID=your-project-id
+
+# Used only by the setup script (scripts/setup-appwrite.cjs)
+# NEVER expose this in the browser
+APPWRITE_API_KEY=your-api-key-with-databases-write-permission