Add budget module and push notifications for transactions

Budget: recurring items CRUD, yearly/monthly projections with no-double-count
logic, and full UI (overview, monthly detail, recurring items manager).

Push notifications: Web Push via VAPID keys, triggered on transaction creation
from n8n. Includes service worker handlers, frontend subscription flow, and
a test button on the Dashboard (temporary).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/seed.py

@@ -1,7 +1,16 @@
 from sqlmodel import Session, select
 
 from app.db import engine
-from app.models.models import Account, AccountType, Bank, Category, Currency
+from app.models.models import (
+    Account,
+    AccountType,
+    Bank,
+    Category,
+    Currency,
+    RecurringFrequency,
+    RecurringItem,
+    RecurringItemType,
+)
 
 DEFAULT_CATEGORIES = [
     ("Groceries", "shopping-cart", "automercado,auto mercado,fresh market,macrobiotica,pricesmart,price smart,grassfedcr,pequeno mundo"),
@@ -45,6 +54,143 @@ DEFAULT_ACCOUNTS = [
 ]
 
 
+DEFAULT_RECURRING_ITEMS = [
+    # Incomes
+    {
+        "name": "Alquiler Apt 1",
+        "amount": 320000,
+        "item_type": RecurringItemType.INCOME,
+        "frequency": RecurringFrequency.MONTHLY,
+        "day_of_month": 1,
+        "notes": "Tenant rent - start of month",
+    },
+    {
+        "name": "Alquiler Apt 2",
+        "amount": 360000,
+        "item_type": RecurringItemType.INCOME,
+        "frequency": RecurringFrequency.MONTHLY,
+        "day_of_month": 15,
+        "notes": "Tenant rent - mid month",
+    },
+    {
+        "name": "Salario Quincenal 1",
+        "amount": 1400000,
+        "item_type": RecurringItemType.INCOME,
+        "frequency": RecurringFrequency.MONTHLY,
+        "day_of_month": 15,
+        "notes": "Net salary - mid month",
+    },
+    {
+        "name": "Salario Quincenal 2",
+        "amount": 1400000,
+        "item_type": RecurringItemType.INCOME,
+        "frequency": RecurringFrequency.MONTHLY,
+        "day_of_month": 30,
+        "notes": "Net salary - end of month",
+    },
+    {
+        "name": "Aguinaldo",
+        "amount": 3000000,
+        "item_type": RecurringItemType.INCOME,
+        "frequency": RecurringFrequency.YEARLY,
+        "month_of_year": 12,
+        "notes": "Yearly bonus",
+    },
+    # Fixed expenses
+    {
+        "name": "Hipoteca",
+        "amount": 450000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.MONTHLY,
+        "notes": "Mortgage payment estimate",
+    },
+    {
+        "name": "Comida y Gasolina",
+        "amount": 300000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.MONTHLY,
+        "notes": "Food & Gas estimate",
+    },
+    {
+        "name": "CNFL",
+        "amount": 50000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.MONTHLY,
+        "notes": "Electricity",
+    },
+    {
+        "name": "Internet",
+        "amount": 50000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.MONTHLY,
+        "notes": "Internet service",
+    },
+    {
+        "name": "Municipalidad",
+        "amount": 30000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.MONTHLY,
+        "override_amounts": {"3": 150000, "6": 150000, "9": 150000, "12": 150000},
+        "notes": "Local gov fees; 150k in property tax quarters",
+    },
+    {
+        "name": "Tennis y Limpieza",
+        "amount": 150000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.MONTHLY,
+        "notes": "Tennis lessons + house cleaning",
+    },
+    # Cash transfers
+    {
+        "name": "Empleada Doméstica",
+        "amount": 20000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.WEEKLY,
+        "day_of_month": 0,
+        "notes": "Weekly maid payment (~80k/month)",
+    },
+    {
+        "name": "Clases de Tennis",
+        "amount": 50000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.MONTHLY,
+        "notes": "Monthly tennis lessons cash transfer",
+    },
+    # Sporadic
+    {
+        "name": "CCE (Country Club)",
+        "amount": 720000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.YEARLY,
+        "month_of_year": 2,
+        "notes": "Yearly country club fee",
+    },
+    {
+        "name": "Seguro Vehicular",
+        "amount": 150000,
+        "item_type": RecurringItemType.EXPENSE,
+        "frequency": RecurringFrequency.BIANNUAL,
+        "month_of_year": 1,
+        "notes": "Car insurance every 6 months (Jan, Jul)",
+    },
+    # Savings
+    {
+        "name": "Ahorro MEMP",
+        "amount": 200000,
+        "item_type": RecurringItemType.SAVINGS,
+        "frequency": RecurringFrequency.MONTHLY,
+        "notes": "Monthly savings to MEMP account",
+    },
+    {
+        "name": "Ahorro MPAT",
+        "amount": 200000,
+        "item_type": RecurringItemType.SAVINGS,
+        "frequency": RecurringFrequency.MONTHLY,
+        "notes": "Monthly savings to MPAT account",
+    },
+]
+
+
 def seed_db():
     with Session(engine) as session:
         existing = session.exec(select(Category)).first()
@@ -58,3 +204,9 @@ def seed_db():
             for bank, currency, label, account_type in DEFAULT_ACCOUNTS:
                 session.add(Account(bank=bank, currency=currency, label=label, account_type=account_type))
             session.commit()
+
+        existing_recurring = session.exec(select(RecurringItem)).first()
+        if not existing_recurring:
+            for item_data in DEFAULT_RECURRING_ITEMS:
+                session.add(RecurringItem(**item_data))
+            session.commit()