Add budget module: FastAPI backend + React frontend

Backend: FastAPI + PostgreSQL with models for accounts, transactions,
and categories. Auto-categorization from merchant patterns, token auth,
CRUD endpoints, and seed data for 16 categories and 4 bank accounts.

Frontend: Login, Dashboard (account balances + recent charges),
Transactions (full CRUD table with search/filter), Cash & Transfers
view. Dark theme with emerald/cyan accents, responsive layout.

Infrastructure: Updated docker-compose for backend + db services,
nginx proxy config for API routing, deploy workflow with secrets.

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

backend/app/models/models.py

@@ -0,0 +1,135 @@
+import enum
+from datetime import datetime
+from typing import Optional
+
+from sqlmodel import Field, Relationship, SQLModel
+
+
+class TransactionType(str, enum.Enum):
+    COMPRA = "COMPRA"
+    DEVOLUCION = "DEVOLUCION"
+
+
+class TransactionSource(str, enum.Enum):
+    CREDIT_CARD = "CREDIT_CARD"
+    CASH = "CASH"
+    TRANSFER = "TRANSFER"
+
+
+class Currency(str, enum.Enum):
+    CRC = "CRC"
+    USD = "USD"
+
+
+class Bank(str, enum.Enum):
+    BAC = "BAC"
+    BCR = "BCR"
+    DAVIVIENDA = "DAVIVIENDA"
+
+
+# --- Category ---
+
+
+class CategoryBase(SQLModel):
+    name: str = Field(index=True, unique=True)
+    icon: str = "tag"
+    auto_match_patterns: Optional[str] = Field(
+        default=None,
+        description="Comma-separated merchant substrings for auto-matching",
+    )
+
+
+class Category(CategoryBase, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    transactions: list["Transaction"] = Relationship(back_populates="category")
+
+
+class CategoryCreate(CategoryBase):
+    pass
+
+
+class CategoryRead(CategoryBase):
+    id: int
+
+
+class CategoryUpdate(SQLModel):
+    name: Optional[str] = None
+    icon: Optional[str] = None
+    auto_match_patterns: Optional[str] = None
+
+
+# --- Account ---
+
+
+class AccountBase(SQLModel):
+    bank: Bank
+    currency: Currency
+    label: str = Field(description="e.g. 'BAC Colones', 'BAC Dólares'")
+    balance: float = 0.0
+
+
+class Account(AccountBase, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    updated_at: datetime = Field(default_factory=datetime.utcnow)
+
+
+class AccountCreate(AccountBase):
+    pass
+
+
+class AccountRead(AccountBase):
+    id: int
+    updated_at: datetime
+
+
+class AccountUpdate(SQLModel):
+    balance: Optional[float] = None
+    label: Optional[str] = None
+
+
+# --- Transaction ---
+
+
+class TransactionBase(SQLModel):
+    amount: float
+    currency: Currency = Currency.CRC
+    merchant: str
+    city: Optional[str] = None
+    date: datetime
+    card_type: Optional[str] = None
+    card_last4: Optional[str] = None
+    authorization_code: Optional[str] = None
+    reference: Optional[str] = None
+    transaction_type: TransactionType = TransactionType.COMPRA
+    source: TransactionSource = TransactionSource.CREDIT_CARD
+    bank: Bank = Bank.BAC
+    notes: Optional[str] = None
+    category_id: Optional[int] = Field(default=None, foreign_key="category.id")
+
+
+class Transaction(TransactionBase, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    created_at: datetime = Field(default_factory=datetime.utcnow)
+    category: Optional[Category] = Relationship(back_populates="transactions")
+
+
+class TransactionCreate(TransactionBase):
+    pass
+
+
+class TransactionRead(TransactionBase):
+    id: int
+    created_at: datetime
+    category: Optional[CategoryRead] = None
+
+
+class TransactionUpdate(SQLModel):
+    amount: Optional[float] = None
+    currency: Optional[Currency] = None
+    merchant: Optional[str] = None
+    city: Optional[str] = None
+    date: Optional[datetime] = None
+    transaction_type: Optional[TransactionType] = None
+    source: Optional[TransactionSource] = None
+    notes: Optional[str] = None
+    category_id: Optional[int] = None