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/api/v1/endpoints/accounts.py

@@ -0,0 +1,51 @@
+from datetime import datetime
+
+from fastapi import APIRouter, Depends, HTTPException
+from sqlmodel import Session, select
+
+from app.auth import get_current_user
+from app.db import get_session
+from app.models.models import Account, AccountCreate, AccountRead, AccountUpdate
+
+router = APIRouter(prefix="/accounts", tags=["accounts"])
+
+
+@router.get("/", response_model=list[AccountRead])
+def list_accounts(
+    session: Session = Depends(get_session),
+    _user: str = Depends(get_current_user),
+):
+    return session.exec(select(Account)).all()
+
+
+@router.post("/", response_model=AccountRead, status_code=201)
+def create_account(
+    data: AccountCreate,
+    session: Session = Depends(get_session),
+    _user: str = Depends(get_current_user),
+):
+    account = Account.model_validate(data)
+    session.add(account)
+    session.commit()
+    session.refresh(account)
+    return account
+
+
+@router.patch("/{account_id}", response_model=AccountRead)
+def update_account(
+    account_id: int,
+    data: AccountUpdate,
+    session: Session = Depends(get_session),
+    _user: str = Depends(get_current_user),
+):
+    account = session.get(Account, account_id)
+    if not account:
+        raise HTTPException(status_code=404, detail="Account not found")
+    update_data = data.model_dump(exclude_unset=True)
+    for key, value in update_data.items():
+        setattr(account, key, value)
+    account.updated_at = datetime.utcnow()
+    session.add(account)
+    session.commit()
+    session.refresh(account)
+    return account